From 9dac796d91a58c9c405b31df6b421999f6d6c822 Mon Sep 17 00:00:00 2001
From: Fred Tempez <ftempez@gmail.com>
Date: Tue, 5 May 2020 17:43:35 +0200
Subject: [PATCH] Update PHPMailer

---
 CHANGES.md                                    |    1 +
 core/class/autoload.php                       |    4 +-
 ...xception.class.php => Exception.class.php} |    2 +-
 ...hpmailer.class.php => PHPMailer.class.php} | 1100 ++++++++++-------
 core/core.php                                 |    2 +-
 5 files changed, 654 insertions(+), 455 deletions(-)
 rename core/class/phpmailer/{exception.class.php => Exception.class.php} (95%)
 mode change 100755 => 100644
 rename core/class/phpmailer/{phpmailer.class.php => PHPMailer.class.php} (81%)
 mode change 100755 => 100644

diff --git a/CHANGES.md b/CHANGES.md
index 477ef2c6..2528de8c 100755
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,7 @@
 - Mises à jour :
     - SimpleLightBox v2.1.4
     - TinyMCE v4.9.9
+    - PHPMailer 6.1.5
 - Améliorations :
     - Architecture de stockage des données.
         - Les données sont désormais stockées dans des fichiers distincts (core, config, theme, user, page et module).
diff --git a/core/class/autoload.php b/core/class/autoload.php
index 9aac3936..156476e0 100755
--- a/core/class/autoload.php
+++ b/core/class/autoload.php
@@ -5,8 +5,8 @@ class autoload {
         require_once 'core/class/helper.class.php';
         require_once 'core/class/template.class.php';
         require_once 'core/class/SitemapGenerator.class.php';
-        require_once 'core/class/phpmailer/phpmailer.class.php';
-        require_once 'core/class/phpmailer/exception.class.php';
+        require_once 'core/class/phpmailer/PHPMailer.class.php';
+        require_once 'core/class/phpmailer/Exception.class.php';
         require_once "core/class/jsondb/Dot.class.php";
         require_once "core/class/jsondb/JsonDb.class.php";
     }
diff --git a/core/class/phpmailer/exception.class.php b/core/class/phpmailer/Exception.class.php
old mode 100755
new mode 100644
similarity index 95%
rename from core/class/phpmailer/exception.class.php
rename to core/class/phpmailer/Exception.class.php
index 9a05dec3..b1e552f5
--- a/core/class/phpmailer/exception.class.php
+++ b/core/class/phpmailer/Exception.class.php
@@ -23,7 +23,7 @@ namespace PHPMailer\PHPMailer;
 /**
  * PHPMailer exception handler.
  *
- * @author  Marcus Bointon <phpmailer@synchromedia.co.uk>
+ * @author Marcus Bointon <phpmailer@synchromedia.co.uk>
  */
 class Exception extends \Exception
 {
diff --git a/core/class/phpmailer/phpmailer.class.php b/core/class/phpmailer/PHPMailer.class.php
old mode 100755
new mode 100644
similarity index 81%
rename from core/class/phpmailer/phpmailer.class.php
rename to core/class/phpmailer/PHPMailer.class.php
index d18c2fbe..51dff921
--- a/core/class/phpmailer/phpmailer.class.php
+++ b/core/class/phpmailer/PHPMailer.class.php
@@ -3,13 +3,13 @@
  * PHPMailer - PHP email creation and transport class.
  * PHP Version 5.5.
  *
- * @see       https://github.com/PHPMailer/PHPMailer/ The PHPMailer GitHub project
+ * @see https://github.com/PHPMailer/PHPMailer/ The PHPMailer GitHub project
  *
  * @author    Marcus Bointon (Synchro/coolbru) <phpmailer@synchromedia.co.uk>
  * @author    Jim Jagielski (jimjag) <jimjag@gmail.com>
  * @author    Andy Prevost (codeworxtech) <codeworxtech@users.sourceforge.net>
  * @author    Brent R. Matzelle (original founder)
- * @copyright 2012 - 2017 Marcus Bointon
+ * @copyright 2012 - 2019 Marcus Bointon
  * @copyright 2010 - 2012 Jim Jagielski
  * @copyright 2004 - 2009 Andy Prevost
  * @license   http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
@@ -23,13 +23,14 @@ namespace PHPMailer\PHPMailer;
 /**
  * PHPMailer - PHP email creation and transport class.
  *
- * @author  Marcus Bointon (Synchro/coolbru) <phpmailer@synchromedia.co.uk>
- * @author  Jim Jagielski (jimjag) <jimjag@gmail.com>
- * @author  Andy Prevost (codeworxtech) <codeworxtech@users.sourceforge.net>
- * @author  Brent R. Matzelle (original founder)
+ * @author Marcus Bointon (Synchro/coolbru) <phpmailer@synchromedia.co.uk>
+ * @author Jim Jagielski (jimjag) <jimjag@gmail.com>
+ * @author Andy Prevost (codeworxtech) <codeworxtech@users.sourceforge.net>
+ * @author Brent R. Matzelle (original founder)
  */
 class PHPMailer
 {
+    const CHARSET_ASCII = 'us-ascii';
     const CHARSET_ISO88591 = 'iso-8859-1';
     const CHARSET_UTF8 = 'utf-8';
 
@@ -46,12 +47,24 @@ class PHPMailer
     const ENCODING_BINARY = 'binary';
     const ENCODING_QUOTED_PRINTABLE = 'quoted-printable';
 
+    const ENCRYPTION_STARTTLS = 'tls';
+    const ENCRYPTION_SMTPS = 'ssl';
+
+    const ICAL_METHOD_REQUEST = 'REQUEST';
+    const ICAL_METHOD_PUBLISH = 'PUBLISH';
+    const ICAL_METHOD_REPLY = 'REPLY';
+    const ICAL_METHOD_ADD = 'ADD';
+    const ICAL_METHOD_CANCEL = 'CANCEL';
+    const ICAL_METHOD_REFRESH = 'REFRESH';
+    const ICAL_METHOD_COUNTER = 'COUNTER';
+    const ICAL_METHOD_DECLINECOUNTER = 'DECLINECOUNTER';
+
     /**
      * Email priority.
      * Options: null (default), 1 = High, 3 = Normal, 5 = low.
      * When null, the header is not set at all.
      *
-     * @var int
+     * @var int|null
      */
     public $Priority;
 
@@ -145,6 +158,22 @@ class PHPMailer
      */
     public $Ical = '';
 
+    /**
+     * Value-array of "method" in Contenttype header "text/calendar"
+     *
+     * @var string[]
+     */
+    protected static $IcalMethods = [
+        self::ICAL_METHOD_REQUEST,
+        self::ICAL_METHOD_PUBLISH,
+        self::ICAL_METHOD_REPLY,
+        self::ICAL_METHOD_ADD,
+        self::ICAL_METHOD_CANCEL,
+        self::ICAL_METHOD_REFRESH,
+        self::ICAL_METHOD_COUNTER,
+        self::ICAL_METHOD_DECLINECOUNTER,
+    ];
+
     /**
      * The complete compiled MIME message body.
      *
@@ -212,6 +241,8 @@ class PHPMailer
      * $_SERVER['SERVER_NAME'], gethostname(), php_uname('n'), or the value
      * 'localhost.localdomain'.
      *
+     * @see PHPMailer::$Helo
+     *
      * @var string
      */
     public $Hostname = '';
@@ -258,7 +289,7 @@ class PHPMailer
     public $Port = 25;
 
     /**
-     * The SMTP HELO of the message.
+     * The SMTP HELO/EHLO name used for the SMTP connection.
      * Default is $Hostname. If $Hostname is empty, PHPMailer attempts to find
      * one with the same method described above for $Hostname.
      *
@@ -270,7 +301,7 @@ class PHPMailer
 
     /**
      * What kind of encryption to use on the SMTP connection.
-     * Options: '', 'ssl' or 'tls'.
+     * Options: '', static::ENCRYPTION_STARTTLS, or static::ENCRYPTION_SMTPS.
      *
      * @var string
      */
@@ -357,11 +388,11 @@ class PHPMailer
      * SMTP class debug output mode.
      * Debug output level.
      * Options:
-     * * `0` No output
-     * * `1` Commands
-     * * `2` Data and commands
-     * * `3` As 2 plus connection status
-     * * `4` Low-level data output.
+     * * SMTP::DEBUG_OFF: No output
+     * * SMTP::DEBUG_CLIENT: Client messages
+     * * SMTP::DEBUG_SERVER: Client and server messages
+     * * SMTP::DEBUG_CONNECTION: As SERVER plus connection status
+     * * SMTP::DEBUG_LOWLEVEL: Noisy, low-level data output, rarely needed
      *
      * @see SMTP::$do_debug
      *
@@ -527,9 +558,9 @@ class PHPMailer
 
     /**
      * What to put in the X-Mailer header.
-     * Options: An empty string for PHPMailer default, whitespace for none, or a string to use.
+     * Options: An empty string for PHPMailer default, whitespace/null for none, or a string to use.
      *
-     * @var string
+     * @var string|null
      */
     public $XMailer = '';
 
@@ -714,7 +745,7 @@ class PHPMailer
      *
      * @var string
      */
-    const VERSION = '6.0.7';
+    const VERSION = '6.1.5';
 
     /**
      * Error severity: message only, continue processing.
@@ -738,11 +769,32 @@ class PHPMailer
     const STOP_CRITICAL = 2;
 
     /**
-     * SMTP RFC standard line ending.
+     * The SMTP standard CRLF line break.
+     * If you want to change line break format, change static::$LE, not this.
+     */
+    const CRLF = "\r\n";
+
+    /**
+     * "Folding White Space" a white space string used for line folding.
+     */
+    const FWS = ' ';
+
+    /**
+     * SMTP RFC standard line ending; Carriage Return, Line Feed.
      *
      * @var string
      */
-    protected static $LE = "\r\n";
+    protected static $LE = self::CRLF;
+
+    /**
+     * The maximum line length supported by mail().
+     *
+     * Background: mail() will sometimes corrupt messages
+     * with headers headers longer than 65 chars, see #818.
+     *
+     * @var int
+     */
+    const MAIL_MAX_LINE_LENGTH = 63;
 
     /**
      * The maximum line length allowed by RFC 2822 section 2.1.1.
@@ -807,7 +859,7 @@ class PHPMailer
             $subject = $this->encodeHeader($this->secureHeader($subject));
         }
         //Calling mail() with null params breaks
-        if (!$this->UseSendmailOptions or null === $params) {
+        if (!$this->UseSendmailOptions || null === $params) {
             $result = @mail($to, $subject, $body, $header);
         } else {
             $result = @mail($to, $subject, $body, $header, $params);
@@ -837,7 +889,7 @@ class PHPMailer
             return;
         }
         //Avoid clash with built-in function names
-        if (!in_array($this->Debugoutput, ['error_log', 'html', 'echo']) and is_callable($this->Debugoutput)) {
+        if (is_callable($this->Debugoutput) && !in_array($this->Debugoutput, ['error_log', 'html', 'echo'])) {
             call_user_func($this->Debugoutput, $str, $this->SMTPDebug);
 
             return;
@@ -858,12 +910,12 @@ class PHPMailer
             case 'echo':
             default:
                 //Normalize line breaks
-                $str = preg_replace('/\r\n|\r/ms', "\n", $str);
+                $str = preg_replace('/\r\n|\r/m', "\n", $str);
                 echo gmdate('Y-m-d H:i:s'),
                 "\t",
                     //Trim trailing space
                 trim(
-                //Indent for readability, except for trailing break
+                    //Indent for readability, except for trailing break
                     str_replace(
                         "\n",
                         "\n                   \t                  ",
@@ -1031,19 +1083,17 @@ class PHPMailer
         }
         $params = [$kind, $address, $name];
         // Enqueue addresses with IDN until we know the PHPMailer::$CharSet.
-        if ($this->has8bitChars(substr($address, ++$pos)) and static::idnSupported()) {
-            if ('Reply-To' != $kind) {
+        if (static::idnSupported() && $this->has8bitChars(substr($address, ++$pos))) {
+            if ('Reply-To' !== $kind) {
                 if (!array_key_exists($address, $this->RecipientsQueue)) {
                     $this->RecipientsQueue[$address] = $params;
 
                     return true;
                 }
-            } else {
-                if (!array_key_exists($address, $this->ReplyToQueue)) {
-                    $this->ReplyToQueue[$address] = $params;
+            } elseif (!array_key_exists($address, $this->ReplyToQueue)) {
+                $this->ReplyToQueue[$address] = $params;
 
-                    return true;
-                }
+                return true;
             }
 
             return false;
@@ -1068,9 +1118,11 @@ class PHPMailer
     protected function addAnAddress($kind, $address, $name = '')
     {
         if (!in_array($kind, ['to', 'cc', 'bcc', 'Reply-To'])) {
-            $error_message = sprintf('%s: %s',
+            $error_message = sprintf(
+                '%s: %s',
                 $this->lang('Invalid recipient kind'),
-                $kind);
+                $kind
+            );
             $this->setError($error_message);
             $this->edebug($error_message);
             if ($this->exceptions) {
@@ -1080,10 +1132,12 @@ class PHPMailer
             return false;
         }
         if (!static::validateAddress($address)) {
-            $error_message = sprintf('%s (%s): %s',
+            $error_message = sprintf(
+                '%s (%s): %s',
                 $this->lang('invalid_address'),
                 $kind,
-                $address);
+                $address
+            );
             $this->setError($error_message);
             $this->edebug($error_message);
             if ($this->exceptions) {
@@ -1092,19 +1146,17 @@ class PHPMailer
 
             return false;
         }
-        if ('Reply-To' != $kind) {
+        if ('Reply-To' !== $kind) {
             if (!array_key_exists(strtolower($address), $this->all_recipients)) {
                 $this->{$kind}[] = [$address, $name];
                 $this->all_recipients[strtolower($address)] = true;
 
                 return true;
             }
-        } else {
-            if (!array_key_exists(strtolower($address), $this->ReplyTo)) {
-                $this->ReplyTo[strtolower($address)] = [$address, $name];
+        } elseif (!array_key_exists(strtolower($address), $this->ReplyTo)) {
+            $this->ReplyTo[strtolower($address)] = [$address, $name];
 
-                return true;
-            }
+            return true;
         }
 
         return false;
@@ -1116,7 +1168,7 @@ class PHPMailer
      * Uses the imap_rfc822_parse_adrlist function if the IMAP extension is available.
      * Note that quotes in the name part are removed.
      *
-     * @see    http://www.andrew.cmu.edu/user/agreen1/testing/mrbs/web/Mail/RFC822.php A more careful implementation
+     * @see http://www.andrew.cmu.edu/user/agreen1/testing/mrbs/web/Mail/RFC822.php A more careful implementation
      *
      * @param string $addrstr The address list string
      * @param bool   $useimap Whether to use the IMAP extension to parse the list
@@ -1126,17 +1178,17 @@ class PHPMailer
     public static function parseAddresses($addrstr, $useimap = true)
     {
         $addresses = [];
-        if ($useimap and function_exists('imap_rfc822_parse_adrlist')) {
+        if ($useimap && function_exists('imap_rfc822_parse_adrlist')) {
             //Use this built-in parser if it's available
             $list = imap_rfc822_parse_adrlist($addrstr, '');
             foreach ($list as $address) {
-                if ('.SYNTAX-ERROR.' != $address->host) {
-                    if (static::validateAddress($address->mailbox . '@' . $address->host)) {
-                        $addresses[] = [
-                            'name' => (property_exists($address, 'personal') ? $address->personal : ''),
-                            'address' => $address->mailbox . '@' . $address->host,
-                        ];
-                    }
+                if (('.SYNTAX-ERROR.' !== $address->host) && static::validateAddress(
+                    $address->mailbox . '@' . $address->host
+                )) {
+                    $addresses[] = [
+                        'name' => (property_exists($address, 'personal') ? $address->personal : ''),
+                        'address' => $address->mailbox . '@' . $address->host,
+                    ];
                 }
             }
         } else {
@@ -1186,12 +1238,15 @@ class PHPMailer
         $name = trim(preg_replace('/[\r\n]+/', '', $name)); //Strip breaks and trim
         // Don't validate now addresses with IDN. Will be done in send().
         $pos = strrpos($address, '@');
-        if (false === $pos or
-            (!$this->has8bitChars(substr($address, ++$pos)) or !static::idnSupported()) and
-            !static::validateAddress($address)) {
-            $error_message = sprintf('%s (From): %s',
+        if ((false === $pos)
+            || ((!$this->has8bitChars(substr($address, ++$pos)) || !static::idnSupported())
+            && !static::validateAddress($address))
+        ) {
+            $error_message = sprintf(
+                '%s (From): %s',
                 $this->lang('invalid_address'),
-                $address);
+                $address
+            );
             $this->setError($error_message);
             $this->edebug($error_message);
             if ($this->exceptions) {
@@ -1202,10 +1257,8 @@ class PHPMailer
         }
         $this->From = $address;
         $this->FromName = $name;
-        if ($auto) {
-            if (empty($this->Sender)) {
-                $this->Sender = $address;
-            }
+        if ($auto && empty($this->Sender)) {
+            $this->Sender = $address;
         }
 
         return true;
@@ -1254,10 +1307,10 @@ class PHPMailer
             $patternselect = static::$validator;
         }
         if (is_callable($patternselect)) {
-            return call_user_func($patternselect, $address);
+            return $patternselect($address);
         }
         //Reject line breaks in addresses; it's valid RFC5322, but not RFC5321
-        if (strpos($address, "\n") !== false or strpos($address, "\r") !== false) {
+        if (strpos($address, "\n") !== false || strpos($address, "\r") !== false) {
             return false;
         }
         switch ($patternselect) {
@@ -1304,7 +1357,7 @@ class PHPMailer
                 );
             case 'php':
             default:
-                return (bool) filter_var($address, FILTER_VALIDATE_EMAIL);
+                return filter_var($address, FILTER_VALIDATE_EMAIL) !== false;
         }
     }
 
@@ -1316,7 +1369,7 @@ class PHPMailer
      */
     public static function idnSupported()
     {
-        return function_exists('idn_to_ascii') and function_exists('mb_convert_encoding');
+        return function_exists('idn_to_ascii') && function_exists('mb_convert_encoding');
     }
 
     /**
@@ -1327,7 +1380,7 @@ class PHPMailer
      * - Conversion to punycode is impossible (e.g. required PHP functions are not available)
      *   or fails for any reason (e.g. domain contains characters not allowed in an IDN).
      *
-     * @see    PHPMailer::$CharSet
+     * @see PHPMailer::$CharSet
      *
      * @param string $address The email address to convert
      *
@@ -1337,17 +1390,23 @@ class PHPMailer
     {
         // Verify we have required functions, CharSet, and at-sign.
         $pos = strrpos($address, '@');
-        if (static::idnSupported() and
-            !empty($this->CharSet) and
-            false !== $pos
+        if (!empty($this->CharSet) &&
+            false !== $pos &&
+            static::idnSupported()
         ) {
             $domain = substr($address, ++$pos);
             // Verify CharSet string is a valid one, and domain properly encoded in this CharSet.
-            if ($this->has8bitChars($domain) and @mb_check_encoding($domain, $this->CharSet)) {
+            if ($this->has8bitChars($domain) && @mb_check_encoding($domain, $this->CharSet)) {
                 $domain = mb_convert_encoding($domain, 'UTF-8', $this->CharSet);
                 //Ignore IDE complaints about this line - method signature changed in PHP 5.4
                 $errorcode = 0;
-                $punycode = idn_to_ascii($domain, $errorcode, INTL_IDNA_VARIANT_UTS46);
+                if (defined('INTL_IDNA_VARIANT_UTS46')) {
+                    $punycode = idn_to_ascii($domain, $errorcode, INTL_IDNA_VARIANT_UTS46);
+                } elseif (defined('INTL_IDNA_VARIANT_2003')) {
+                    $punycode = idn_to_ascii($domain, $errorcode, INTL_IDNA_VARIANT_2003);
+                } else {
+                    $punycode = idn_to_ascii($domain, $errorcode);
+                }
                 if (false !== $punycode) {
                     return substr($address, 0, $pos) . $punycode;
                 }
@@ -1393,24 +1452,22 @@ class PHPMailer
      */
     public function preSend()
     {
-        if ('smtp' == $this->Mailer or
-            ('mail' == $this->Mailer and stripos(PHP_OS, 'WIN') === 0)
+        if ('smtp' === $this->Mailer
+            || ('mail' === $this->Mailer && stripos(PHP_OS, 'WIN') === 0)
         ) {
             //SMTP mandates RFC-compliant line endings
             //and it's also used with mail() on Windows
-            static::setLE("\r\n");
+            static::setLE(self::CRLF);
         } else {
             //Maintain backward compatibility with legacy Linux command line mailers
             static::setLE(PHP_EOL);
         }
         //Check for buggy PHP versions that add a header with an incorrect line break
-        if (ini_get('mail.add_x_header') == 1
-            and 'mail' == $this->Mailer
-            and stripos(PHP_OS, 'WIN') === 0
-            and ((version_compare(PHP_VERSION, '7.0.0', '>=')
-                    and version_compare(PHP_VERSION, '7.0.17', '<'))
-                or (version_compare(PHP_VERSION, '7.1.0', '>=')
-                    and version_compare(PHP_VERSION, '7.1.3', '<')))
+        if ('mail' === $this->Mailer
+            && ((PHP_VERSION_ID >= 70000 && PHP_VERSION_ID < 70017)
+                || (PHP_VERSION_ID >= 70100 && PHP_VERSION_ID < 70103))
+            && ini_get('mail.add_x_header') === '1'
+            && stripos(PHP_OS, 'WIN') === 0
         ) {
             trigger_error(
                 'Your version of PHP is affected by a bug that may result in corrupted messages.' .
@@ -1441,10 +1498,12 @@ class PHPMailer
                 }
                 $this->$address_kind = $this->punyencodeAddress($this->$address_kind);
                 if (!static::validateAddress($this->$address_kind)) {
-                    $error_message = sprintf('%s (%s): %s',
+                    $error_message = sprintf(
+                        '%s (%s): %s',
                         $this->lang('invalid_address'),
                         $address_kind,
-                        $this->$address_kind);
+                        $this->$address_kind
+                    );
                     $this->setError($error_message);
                     $this->edebug($error_message);
                     if ($this->exceptions) {
@@ -1462,7 +1521,7 @@ class PHPMailer
 
             $this->setMessageType();
             // Refuse to send an empty message unless we are specifically allowing it
-            if (!$this->AllowEmpty and empty($this->Body)) {
+            if (!$this->AllowEmpty && empty($this->Body)) {
                 throw new Exception($this->lang('empty_message'), self::STOP_CRITICAL);
             }
 
@@ -1478,7 +1537,7 @@ class PHPMailer
 
             // To capture the complete message when using mail(), create
             // an extra header list which createHeader() doesn't fold in
-            if ('mail' == $this->Mailer) {
+            if ('mail' === $this->Mailer) {
                 if (count($this->to) > 0) {
                     $this->mailHeader .= $this->addrAppend('To', $this->to);
                 } else {
@@ -1492,11 +1551,11 @@ class PHPMailer
 
             // Sign with DKIM if enabled
             if (!empty($this->DKIM_domain)
-                and !empty($this->DKIM_selector)
-                and (!empty($this->DKIM_private_string)
-                    or (!empty($this->DKIM_private)
-                        and static::isPermittedPath($this->DKIM_private)
-                        and file_exists($this->DKIM_private)
+                && !empty($this->DKIM_selector)
+                && (!empty($this->DKIM_private_string)
+                    || (!empty($this->DKIM_private)
+                        && static::isPermittedPath($this->DKIM_private)
+                        && file_exists($this->DKIM_private)
                     )
                 )
             ) {
@@ -1505,7 +1564,7 @@ class PHPMailer
                     $this->encodeHeader($this->secureHeader($this->Subject)),
                     $this->MIMEBody
                 );
-                $this->MIMEHeader = rtrim($this->MIMEHeader, "\r\n ") . static::$LE .
+                $this->MIMEHeader = static::stripTrailingWSP($this->MIMEHeader) . static::$LE .
                     static::normalizeBreaks($header_dkim) . static::$LE;
             }
 
@@ -1561,7 +1620,7 @@ class PHPMailer
     /**
      * Send mail using the $Sendmail program.
      *
-     * @see    PHPMailer::$Sendmail
+     * @see PHPMailer::$Sendmail
      *
      * @param string $header The message headers
      * @param string $body   The message body
@@ -1572,19 +1631,19 @@ class PHPMailer
      */
     protected function sendmailSend($header, $body)
     {
+        $header = static::stripTrailingWSP($header) . static::$LE . static::$LE;
+
         // CVE-2016-10033, CVE-2016-10045: Don't pass -f if characters will be escaped.
-        if (!empty($this->Sender) and self::isShellSafe($this->Sender)) {
-            if ('qmail' == $this->Mailer) {
+        if (!empty($this->Sender) && self::isShellSafe($this->Sender)) {
+            if ('qmail' === $this->Mailer) {
                 $sendmailFmt = '%s -f%s';
             } else {
                 $sendmailFmt = '%s -oi -f%s -t';
             }
+        } elseif ('qmail' === $this->Mailer) {
+            $sendmailFmt = '%s';
         } else {
-            if ('qmail' == $this->Mailer) {
-                $sendmailFmt = '%s';
-            } else {
-                $sendmailFmt = '%s -oi -t';
-            }
+            $sendmailFmt = '%s -oi -t';
         }
 
         $sendmail = sprintf($sendmailFmt, escapeshellcmd($this->Sendmail), $this->Sender);
@@ -1600,7 +1659,7 @@ class PHPMailer
                 fwrite($mail, $body);
                 $result = pclose($mail);
                 $this->doCallback(
-                    ($result == 0),
+                    ($result === 0),
                     [$toAddr],
                     $this->cc,
                     $this->bcc,
@@ -1622,7 +1681,7 @@ class PHPMailer
             fwrite($mail, $body);
             $result = pclose($mail);
             $this->doCallback(
-                ($result == 0),
+                ($result === 0),
                 $this->to,
                 $this->cc,
                 $this->bcc,
@@ -1653,7 +1712,7 @@ class PHPMailer
     {
         // Future-proof
         if (escapeshellcmd($string) !== $string
-            or !in_array(escapeshellarg($string), ["'$string'", "\"$string\""])
+            || !in_array(escapeshellarg($string), ["'$string'", "\"$string\""])
         ) {
             return false;
         }
@@ -1691,7 +1750,7 @@ class PHPMailer
     /**
      * Send mail using the PHP mail() function.
      *
-     * @see    http://www.php.net/manual/en/book.mail.php
+     * @see http://www.php.net/manual/en/book.mail.php
      *
      * @param string $header The message headers
      * @param string $body   The message body
@@ -1702,6 +1761,8 @@ class PHPMailer
      */
     protected function mailSend($header, $body)
     {
+        $header = static::stripTrailingWSP($header) . static::$LE . static::$LE;
+
         $toArr = [];
         foreach ($this->to as $toaddr) {
             $toArr[] = $this->addrFormat($toaddr);
@@ -1710,24 +1771,22 @@ class PHPMailer
 
         $params = null;
         //This sets the SMTP envelope sender which gets turned into a return-path header by the receiver
-        if (!empty($this->Sender) and static::validateAddress($this->Sender)) {
-            //A space after `-f` is optional, but there is a long history of its presence
-            //causing problems, so we don't use one
-            //Exim docs: http://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_exim_command_line.html
-            //Sendmail docs: http://www.sendmail.org/~ca/email/man/sendmail.html
-            //Qmail docs: http://www.qmail.org/man/man8/qmail-inject.html
-            //Example problem: https://www.drupal.org/node/1057954
-            // CVE-2016-10033, CVE-2016-10045: Don't pass -f if characters will be escaped.
-            if (self::isShellSafe($this->Sender)) {
-                $params = sprintf('-f%s', $this->Sender);
-            }
+        //A space after `-f` is optional, but there is a long history of its presence
+        //causing problems, so we don't use one
+        //Exim docs: http://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_exim_command_line.html
+        //Sendmail docs: http://www.sendmail.org/~ca/email/man/sendmail.html
+        //Qmail docs: http://www.qmail.org/man/man8/qmail-inject.html
+        //Example problem: https://www.drupal.org/node/1057954
+        // CVE-2016-10033, CVE-2016-10045: Don't pass -f if characters will be escaped.
+        if (!empty($this->Sender) && static::validateAddress($this->Sender) && self::isShellSafe($this->Sender)) {
+            $params = sprintf('-f%s', $this->Sender);
         }
-        if (!empty($this->Sender) and static::validateAddress($this->Sender)) {
+        if (!empty($this->Sender) && static::validateAddress($this->Sender)) {
             $old_from = ini_get('sendmail_from');
             ini_set('sendmail_from', $this->Sender);
         }
         $result = false;
-        if ($this->SingleTo and count($toArr) > 1) {
+        if ($this->SingleTo && count($toArr) > 1) {
             foreach ($toArr as $toAddr) {
                 $result = $this->mailPassthru($toAddr, $this->Subject, $body, $header, $params);
                 $this->doCallback($result, [$toAddr], $this->cc, $this->bcc, $this->Subject, $body, $this->From, []);
@@ -1765,8 +1824,6 @@ class PHPMailer
     /**
      * Provide an instance to use for SMTP operations.
      *
-     * @param SMTP $smtp
-     *
      * @return SMTP
      */
     public function setSMTPInstance(SMTP $smtp)
@@ -1793,12 +1850,13 @@ class PHPMailer
      */
     protected function smtpSend($header, $body)
     {
+        $header = static::stripTrailingWSP($header) . static::$LE . static::$LE;
         $bad_rcpt = [];
         if (!$this->smtpConnect($this->SMTPOptions)) {
             throw new Exception($this->lang('smtp_connect_failed'), self::STOP_CRITICAL);
         }
         //Sender already validated in preSend()
-        if ('' == $this->Sender) {
+        if ('' === $this->Sender) {
             $smtp_from = $this->From;
         } else {
             $smtp_from = $this->Sender;
@@ -1825,7 +1883,7 @@ class PHPMailer
         }
 
         // Only send the DATA command if we have viable recipients
-        if ((count($this->all_recipients) > count($bad_rcpt)) and !$this->smtp->data($header . $body)) {
+        if ((count($this->all_recipients) > count($bad_rcpt)) && !$this->smtp->data($header . $body)) {
             throw new Exception($this->lang('data_not_accepted'), self::STOP_CRITICAL);
         }
 
@@ -1857,10 +1915,7 @@ class PHPMailer
             foreach ($bad_rcpt as $bad) {
                 $errstr .= $bad['to'] . ': ' . $bad['error'];
             }
-            throw new Exception(
-                $this->lang('recipients_failed') . $errstr,
-                self::STOP_CONTINUE
-            );
+            throw new Exception($this->lang('recipients_failed') . $errstr, self::STOP_CONTINUE);
         }
 
         return true;
@@ -1904,50 +1959,49 @@ class PHPMailer
         foreach ($hosts as $hostentry) {
             $hostinfo = [];
             if (!preg_match(
-                '/^((ssl|tls):\/\/)*([a-zA-Z0-9\.-]*|\[[a-fA-F0-9:]+\]):?([0-9]*)$/',
+                '/^(?:(ssl|tls):\/\/)?(.+?)(?::(\d+))?$/',
                 trim($hostentry),
                 $hostinfo
             )) {
-                static::edebug($this->lang('connect_host') . ' ' . $hostentry);
+                $this->edebug($this->lang('invalid_hostentry') . ' ' . trim($hostentry));
                 // Not a valid host entry
                 continue;
             }
-            // $hostinfo[2]: optional ssl or tls prefix
-            // $hostinfo[3]: the hostname
-            // $hostinfo[4]: optional port number
+            // $hostinfo[1]: optional ssl or tls prefix
+            // $hostinfo[2]: the hostname
+            // $hostinfo[3]: optional port number
             // The host string prefix can temporarily override the current setting for SMTPSecure
             // If it's not specified, the default value is used
 
             //Check the host name is a valid name or IP address before trying to use it
-            if (!static::isValidHost($hostinfo[3])) {
-                static::edebug($this->lang('connect_host') . ' ' . $hostentry);
+            if (!static::isValidHost($hostinfo[2])) {
+                $this->edebug($this->lang('invalid_host') . ' ' . $hostinfo[2]);
                 continue;
             }
             $prefix = '';
             $secure = $this->SMTPSecure;
-            $tls = ('tls' == $this->SMTPSecure);
-            if ('ssl' == $hostinfo[2] or ('' == $hostinfo[2] and 'ssl' == $this->SMTPSecure)) {
+            $tls = (static::ENCRYPTION_STARTTLS === $this->SMTPSecure);
+            if ('ssl' === $hostinfo[1] || ('' === $hostinfo[1] && static::ENCRYPTION_SMTPS === $this->SMTPSecure)) {
                 $prefix = 'ssl://';
                 $tls = false; // Can't have SSL and TLS at the same time
-                $secure = 'ssl';
-            } elseif ('tls' == $hostinfo[2]) {
+                $secure = static::ENCRYPTION_SMTPS;
+            } elseif ('tls' === $hostinfo[1]) {
                 $tls = true;
                 // tls doesn't use a prefix
-                $secure = 'tls';
+                $secure = static::ENCRYPTION_STARTTLS;
             }
             //Do we need the OpenSSL extension?
             $sslext = defined('OPENSSL_ALGO_SHA256');
-            if ('tls' === $secure or 'ssl' === $secure) {
+            if (static::ENCRYPTION_STARTTLS === $secure || static::ENCRYPTION_SMTPS === $secure) {
                 //Check for an OpenSSL constant rather than using extension_loaded, which is sometimes disabled
                 if (!$sslext) {
                     throw new Exception($this->lang('extension_missing') . 'openssl', self::STOP_CRITICAL);
                 }
             }
-            $host = $hostinfo[3];
+            $host = $hostinfo[2];
             $port = $this->Port;
-            $tport = (int) $hostinfo[4];
-            if ($tport > 0 and $tport < 65536) {
-                $port = $tport;
+            if (array_key_exists(3, $hostinfo) && is_numeric($hostinfo[3]) && $hostinfo[3] > 0 && $hostinfo[3] < 65536) {
+                $port = (int) $hostinfo[3];
             }
             if ($this->smtp->connect($prefix . $host, $port, $this->Timeout, $options)) {
                 try {
@@ -1962,7 +2016,7 @@ class PHPMailer
                     // * we have openssl extension
                     // * we are not already using SSL
                     // * the server offers STARTTLS
-                    if ($this->SMTPAutoTLS and $sslext and 'ssl' != $secure and $this->smtp->getServerExt('STARTTLS')) {
+                    if ($this->SMTPAutoTLS && $sslext && 'ssl' !== $secure && $this->smtp->getServerExt('STARTTLS')) {
                         $tls = true;
                     }
                     if ($tls) {
@@ -1972,16 +2026,13 @@ class PHPMailer
                         // We must resend EHLO after TLS negotiation
                         $this->smtp->hello($hello);
                     }
-                    if ($this->SMTPAuth) {
-                        if (!$this->smtp->authenticate(
-                            $this->Username,
-                            $this->Password,
-                            $this->AuthType,
-                            $this->oauth
-                        )
-                        ) {
-                            throw new Exception($this->lang('authenticate'));
-                        }
+                    if ($this->SMTPAuth && !$this->smtp->authenticate(
+                        $this->Username,
+                        $this->Password,
+                        $this->AuthType,
+                        $this->oauth
+                    )) {
+                        throw new Exception($this->lang('authenticate'));
                     }
 
                     return true;
@@ -1996,7 +2047,7 @@ class PHPMailer
         // If we get here, all connection attempts have failed, so close connection hard
         $this->smtp->close();
         // As we've caught all exceptions, just report whatever the last one was
-        if ($this->exceptions and null !== $lastexception) {
+        if ($this->exceptions && null !== $lastexception) {
             throw $lastexception;
         }
 
@@ -2008,11 +2059,9 @@ class PHPMailer
      */
     public function smtpClose()
     {
-        if (null !== $this->smtp) {
-            if ($this->smtp->connected()) {
-                $this->smtp->quit();
-                $this->smtp->close();
-            }
+        if ((null !== $this->smtp) && $this->smtp->connected()) {
+            $this->smtp->quit();
+            $this->smtp->close();
         }
     }
 
@@ -2037,6 +2086,7 @@ class PHPMailer
             'se' => 'sv',
             'rs' => 'sr',
             'tg' => 'tl',
+            'am' => 'hy',
         ];
 
         if (isset($renamed_langcodes[$langcode])) {
@@ -2056,6 +2106,8 @@ class PHPMailer
             'from_failed' => 'The following From address failed: ',
             'instantiate' => 'Could not instantiate mail function.',
             'invalid_address' => 'Invalid address: ',
+            'invalid_hostentry' => 'Invalid hostentry: ',
+            'invalid_host' => 'Invalid host: ',
             'mailer_not_supported' => ' mailer is not supported.',
             'provide_address' => 'You must provide at least one recipient email address.',
             'recipients_failed' => 'SMTP Error: The following recipients failed: ',
@@ -2076,7 +2128,7 @@ class PHPMailer
         $foundlang = true;
         $lang_file = $lang_path . 'phpmailer.lang-' . $langcode . '.php';
         // There is no English translation file
-        if ('en' != $langcode) {
+        if ('en' !== $langcode) {
             // Make sure language file path is readable
             if (!static::isPermittedPath($lang_file) || !file_exists($lang_file)) {
                 $foundlang = false;
@@ -2136,9 +2188,8 @@ class PHPMailer
             return $this->secureHeader($addr[0]);
         }
 
-        return $this->encodeHeader($this->secureHeader($addr[1]), 'phrase') . ' <' . $this->secureHeader(
-                $addr[0]
-            ) . '>';
+        return $this->encodeHeader($this->secureHeader($addr[1]), 'phrase') .
+            ' <' . $this->secureHeader($addr[0]) . '>';
     }
 
     /**
@@ -2168,7 +2219,7 @@ class PHPMailer
 
         $message = static::normalizeBreaks($message);
         //Remove a trailing line break
-        if (substr($message, -$lelen) == static::$LE) {
+        if (substr($message, -$lelen) === static::$LE) {
             $message = substr($message, 0, -$lelen);
         }
 
@@ -2181,16 +2232,16 @@ class PHPMailer
             $buf = '';
             $firstword = true;
             foreach ($words as $word) {
-                if ($qp_mode and (strlen($word) > $length)) {
+                if ($qp_mode && (strlen($word) > $length)) {
                     $space_left = $length - strlen($buf) - $crlflen;
                     if (!$firstword) {
                         if ($space_left > 20) {
                             $len = $space_left;
                             if ($is_utf8) {
                                 $len = $this->utf8CharBoundary($word, $len);
-                            } elseif ('=' == substr($word, $len - 1, 1)) {
+                            } elseif ('=' === substr($word, $len - 1, 1)) {
                                 --$len;
-                            } elseif ('=' == substr($word, $len - 2, 1)) {
+                            } elseif ('=' === substr($word, $len - 2, 1)) {
                                 $len -= 2;
                             }
                             $part = substr($word, 0, $len);
@@ -2202,22 +2253,22 @@ class PHPMailer
                         }
                         $buf = '';
                     }
-                    while (strlen($word) > 0) {
+                    while ($word !== '') {
                         if ($length <= 0) {
                             break;
                         }
                         $len = $length;
                         if ($is_utf8) {
                             $len = $this->utf8CharBoundary($word, $len);
-                        } elseif ('=' == substr($word, $len - 1, 1)) {
+                        } elseif ('=' === substr($word, $len - 1, 1)) {
                             --$len;
-                        } elseif ('=' == substr($word, $len - 2, 1)) {
+                        } elseif ('=' === substr($word, $len - 2, 1)) {
                             $len -= 2;
                         }
                         $part = substr($word, 0, $len);
-                        $word = substr($word, $len);
+                        $word = (string) substr($word, $len);
 
-                        if (strlen($word) > 0) {
+                        if ($word !== '') {
                             $message .= $part . sprintf('=%s', static::$LE);
                         } else {
                             $buf = $part;
@@ -2230,7 +2281,7 @@ class PHPMailer
                     }
                     $buf .= $word;
 
-                    if (strlen($buf) > $length and '' != $buf_o) {
+                    if ('' !== $buf_o && strlen($buf) > $length) {
                         $message .= $buf_o . $soft_break;
                         $buf = $word;
                     }
@@ -2325,23 +2376,21 @@ class PHPMailer
     {
         $result = '';
 
-        $result .= $this->headerLine('Date', '' == $this->MessageDate ? self::rfcDate() : $this->MessageDate);
+        $result .= $this->headerLine('Date', '' === $this->MessageDate ? self::rfcDate() : $this->MessageDate);
 
         // To be created automatically by mail()
         if ($this->SingleTo) {
-            if ('mail' != $this->Mailer) {
+            if ('mail' !== $this->Mailer) {
                 foreach ($this->to as $toaddr) {
                     $this->SingleToArray[] = $this->addrFormat($toaddr);
                 }
             }
-        } else {
-            if (count($this->to) > 0) {
-                if ('mail' != $this->Mailer) {
-                    $result .= $this->addrAppend('To', $this->to);
-                }
-            } elseif (count($this->cc) == 0) {
-                $result .= $this->headerLine('To', 'undisclosed-recipients:;');
+        } elseif (count($this->to) > 0) {
+            if ('mail' !== $this->Mailer) {
+                $result .= $this->addrAppend('To', $this->to);
             }
+        } elseif (count($this->cc) === 0) {
+            $result .= $this->headerLine('To', 'undisclosed-recipients:;');
         }
 
         $result .= $this->addrAppend('From', [[trim($this->From), $this->FromName]]);
@@ -2353,9 +2402,9 @@ class PHPMailer
 
         // sendmail and mail() extract Bcc from the header before sending
         if ((
-                'sendmail' == $this->Mailer or 'qmail' == $this->Mailer or 'mail' == $this->Mailer
+                'sendmail' === $this->Mailer || 'qmail' === $this->Mailer || 'mail' === $this->Mailer
             )
-            and count($this->bcc) > 0
+            && count($this->bcc) > 0
         ) {
             $result .= $this->addrAppend('Bcc', $this->bcc);
         }
@@ -2365,13 +2414,13 @@ class PHPMailer
         }
 
         // mail() sets the subject itself
-        if ('mail' != $this->Mailer) {
+        if ('mail' !== $this->Mailer) {
             $result .= $this->headerLine('Subject', $this->encodeHeader($this->secureHeader($this->Subject)));
         }
 
         // Only allow a custom message ID if it conforms to RFC 5322 section 3.6.4
         // https://tools.ietf.org/html/rfc5322#section-3.6.4
-        if ('' != $this->MessageID and preg_match('/^<.*@.*>$/', $this->MessageID)) {
+        if ('' !== $this->MessageID && preg_match('/^<.*@.*>$/', $this->MessageID)) {
             $this->lastMessageID = $this->MessageID;
         } else {
             $this->lastMessageID = sprintf('<%s@%s>', $this->uniqueid, $this->serverHostname());
@@ -2380,7 +2429,7 @@ class PHPMailer
         if (null !== $this->Priority) {
             $result .= $this->headerLine('X-Priority', $this->Priority);
         }
-        if ('' == $this->XMailer) {
+        if ('' === $this->XMailer) {
             $result .= $this->headerLine(
                 'X-Mailer',
                 'PHPMailer ' . self::VERSION . ' (https://github.com/PHPMailer/PHPMailer)'
@@ -2392,7 +2441,7 @@ class PHPMailer
             }
         }
 
-        if ('' != $this->ConfirmReadingTo) {
+        if ('' !== $this->ConfirmReadingTo) {
             $result .= $this->headerLine('Disposition-Notification-To', '<' . $this->ConfirmReadingTo . '>');
         }
 
@@ -2444,10 +2493,10 @@ class PHPMailer
                 break;
         }
         // RFC1341 part 5 says 7bit is assumed if not specified
-        if (static::ENCODING_7BIT != $this->Encoding) {
+        if (static::ENCODING_7BIT !== $this->Encoding) {
             // RFC 2045 section 6.4 says multipart MIME parts may only use 7bit, 8bit or binary CTE
             if ($ismultipart) {
-                if (static::ENCODING_8BIT == $this->Encoding) {
+                if (static::ENCODING_8BIT === $this->Encoding) {
                     $result .= $this->headerLine('Content-Transfer-Encoding', static::ENCODING_8BIT);
                 }
                 // The only remaining alternatives are quoted-printable and base64, which are both 7bit compatible
@@ -2456,8 +2505,8 @@ class PHPMailer
             }
         }
 
-        if ('mail' != $this->Mailer) {
-            $result .= static::$LE;
+        if ('mail' !== $this->Mailer) {
+//            $result .= static::$LE;
         }
 
         return $result;
@@ -2474,7 +2523,8 @@ class PHPMailer
      */
     public function getSentMIMEMessage()
     {
-        return rtrim($this->MIMEHeader . $this->mailHeader, "\n\r") . static::$LE . static::$LE . $this->MIMEBody;
+        return static::stripTrailingWSP($this->MIMEHeader . $this->mailHeader) .
+            static::$LE . static::$LE . $this->MIMEBody;
     }
 
     /**
@@ -2485,11 +2535,19 @@ class PHPMailer
     protected function generateId()
     {
         $len = 32; //32 bytes = 256 bits
+        $bytes = '';
         if (function_exists('random_bytes')) {
-            $bytes = random_bytes($len);
+            try {
+                $bytes = random_bytes($len);
+            } catch (\Exception $e) {
+                //Do nothing
+            }
         } elseif (function_exists('openssl_random_pseudo_bytes')) {
+            /** @noinspection CryptographicallySecureRandomnessInspection */
             $bytes = openssl_random_pseudo_bytes($len);
-        } else {
+        }
+        if ($bytes === '') {
+            //We failed to produce a proper random string, so make do.
             //Use a hash to force the length to the same as the other methods
             $bytes = hash('sha256', uniqid((string) mt_rand(), true), true);
         }
@@ -2524,32 +2582,32 @@ class PHPMailer
         $bodyEncoding = $this->Encoding;
         $bodyCharSet = $this->CharSet;
         //Can we do a 7-bit downgrade?
-        if (static::ENCODING_8BIT == $bodyEncoding and !$this->has8bitChars($this->Body)) {
+        if (static::ENCODING_8BIT === $bodyEncoding && !$this->has8bitChars($this->Body)) {
             $bodyEncoding = static::ENCODING_7BIT;
             //All ISO 8859, Windows codepage and UTF-8 charsets are ascii compatible up to 7-bit
-            $bodyCharSet = 'us-ascii';
+            $bodyCharSet = static::CHARSET_ASCII;
         }
         //If lines are too long, and we're not already using an encoding that will shorten them,
         //change to quoted-printable transfer encoding for the body part only
-        if (static::ENCODING_BASE64 != $this->Encoding and static::hasLineLongerThanMax($this->Body)) {
+        if (static::ENCODING_BASE64 !== $this->Encoding && static::hasLineLongerThanMax($this->Body)) {
             $bodyEncoding = static::ENCODING_QUOTED_PRINTABLE;
         }
 
         $altBodyEncoding = $this->Encoding;
         $altBodyCharSet = $this->CharSet;
         //Can we do a 7-bit downgrade?
-        if (static::ENCODING_8BIT == $altBodyEncoding and !$this->has8bitChars($this->AltBody)) {
+        if (static::ENCODING_8BIT === $altBodyEncoding && !$this->has8bitChars($this->AltBody)) {
             $altBodyEncoding = static::ENCODING_7BIT;
             //All ISO 8859, Windows codepage and UTF-8 charsets are ascii compatible up to 7-bit
-            $altBodyCharSet = 'us-ascii';
+            $altBodyCharSet = static::CHARSET_ASCII;
         }
         //If lines are too long, and we're not already using an encoding that will shorten them,
         //change to quoted-printable transfer encoding for the alt body part only
-        if (static::ENCODING_BASE64 != $altBodyEncoding and static::hasLineLongerThanMax($this->AltBody)) {
+        if (static::ENCODING_BASE64 !== $altBodyEncoding && static::hasLineLongerThanMax($this->AltBody)) {
             $altBodyEncoding = static::ENCODING_QUOTED_PRINTABLE;
         }
         //Use this as a preamble in all multipart message types
-        $mimepre = 'This is a multi-part message in MIME format.' . static::$LE;
+        $mimepre = 'This is a multi-part message in MIME format.' . static::$LE  . static::$LE;
         switch ($this->message_type) {
             case 'inline':
                 $body .= $mimepre;
@@ -2581,14 +2639,36 @@ class PHPMailer
                 break;
             case 'alt':
                 $body .= $mimepre;
-                $body .= $this->getBoundary($this->boundary[1], $altBodyCharSet, static::CONTENT_TYPE_PLAINTEXT, $altBodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[1],
+                    $altBodyCharSet,
+                    static::CONTENT_TYPE_PLAINTEXT,
+                    $altBodyEncoding
+                );
                 $body .= $this->encodeString($this->AltBody, $altBodyEncoding);
                 $body .= static::$LE;
-                $body .= $this->getBoundary($this->boundary[1], $bodyCharSet, static::CONTENT_TYPE_TEXT_HTML, $bodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[1],
+                    $bodyCharSet,
+                    static::CONTENT_TYPE_TEXT_HTML,
+                    $bodyEncoding
+                );
                 $body .= $this->encodeString($this->Body, $bodyEncoding);
                 $body .= static::$LE;
                 if (!empty($this->Ical)) {
-                    $body .= $this->getBoundary($this->boundary[1], '', static::CONTENT_TYPE_TEXT_CALENDAR . '; method=REQUEST', '');
+                    $method = static::ICAL_METHOD_REQUEST;
+                    foreach (static::$IcalMethods as $imethod) {
+                        if (stripos($this->Ical, 'METHOD:' . $imethod) !== false) {
+                            $method = $imethod;
+                            break;
+                        }
+                    }
+                    $body .= $this->getBoundary(
+                        $this->boundary[1],
+                        '',
+                        static::CONTENT_TYPE_TEXT_CALENDAR . '; method=' . $method,
+                        ''
+                    );
                     $body .= $this->encodeString($this->Ical, $this->Encoding);
                     $body .= static::$LE;
                 }
@@ -2596,7 +2676,12 @@ class PHPMailer
                 break;
             case 'alt_inline':
                 $body .= $mimepre;
-                $body .= $this->getBoundary($this->boundary[1], $altBodyCharSet, static::CONTENT_TYPE_PLAINTEXT, $altBodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[1],
+                    $altBodyCharSet,
+                    static::CONTENT_TYPE_PLAINTEXT,
+                    $altBodyEncoding
+                );
                 $body .= $this->encodeString($this->AltBody, $altBodyEncoding);
                 $body .= static::$LE;
                 $body .= $this->textLine('--' . $this->boundary[1]);
@@ -2604,7 +2689,12 @@ class PHPMailer
                 $body .= $this->textLine(' boundary="' . $this->boundary[2] . '";');
                 $body .= $this->textLine(' type="' . static::CONTENT_TYPE_TEXT_HTML . '"');
                 $body .= static::$LE;
-                $body .= $this->getBoundary($this->boundary[2], $bodyCharSet, static::CONTENT_TYPE_TEXT_HTML, $bodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[2],
+                    $bodyCharSet,
+                    static::CONTENT_TYPE_TEXT_HTML,
+                    $bodyEncoding
+                );
                 $body .= $this->encodeString($this->Body, $bodyEncoding);
                 $body .= static::$LE;
                 $body .= $this->attachAll('inline', $this->boundary[2]);
@@ -2617,14 +2707,36 @@ class PHPMailer
                 $body .= $this->headerLine('Content-Type', static::CONTENT_TYPE_MULTIPART_ALTERNATIVE . ';');
                 $body .= $this->textLine(' boundary="' . $this->boundary[2] . '"');
                 $body .= static::$LE;
-                $body .= $this->getBoundary($this->boundary[2], $altBodyCharSet, static::CONTENT_TYPE_PLAINTEXT, $altBodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[2],
+                    $altBodyCharSet,
+                    static::CONTENT_TYPE_PLAINTEXT,
+                    $altBodyEncoding
+                );
                 $body .= $this->encodeString($this->AltBody, $altBodyEncoding);
                 $body .= static::$LE;
-                $body .= $this->getBoundary($this->boundary[2], $bodyCharSet, static::CONTENT_TYPE_TEXT_HTML, $bodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[2],
+                    $bodyCharSet,
+                    static::CONTENT_TYPE_TEXT_HTML,
+                    $bodyEncoding
+                );
                 $body .= $this->encodeString($this->Body, $bodyEncoding);
                 $body .= static::$LE;
                 if (!empty($this->Ical)) {
-                    $body .= $this->getBoundary($this->boundary[2], '', static::CONTENT_TYPE_TEXT_CALENDAR . '; method=REQUEST', '');
+                    $method = static::ICAL_METHOD_REQUEST;
+                    foreach (static::$IcalMethods as $imethod) {
+                        if (stripos($this->Ical, 'METHOD:' . $imethod) !== false) {
+                            $method = $imethod;
+                            break;
+                        }
+                    }
+                    $body .= $this->getBoundary(
+                        $this->boundary[2],
+                        '',
+                        static::CONTENT_TYPE_TEXT_CALENDAR . '; method=' . $method,
+                        ''
+                    );
                     $body .= $this->encodeString($this->Ical, $this->Encoding);
                 }
                 $body .= $this->endBoundary($this->boundary[2]);
@@ -2637,7 +2749,12 @@ class PHPMailer
                 $body .= $this->headerLine('Content-Type', static::CONTENT_TYPE_MULTIPART_ALTERNATIVE . ';');
                 $body .= $this->textLine(' boundary="' . $this->boundary[2] . '"');
                 $body .= static::$LE;
-                $body .= $this->getBoundary($this->boundary[2], $altBodyCharSet, static::CONTENT_TYPE_PLAINTEXT, $altBodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[2],
+                    $altBodyCharSet,
+                    static::CONTENT_TYPE_PLAINTEXT,
+                    $altBodyEncoding
+                );
                 $body .= $this->encodeString($this->AltBody, $altBodyEncoding);
                 $body .= static::$LE;
                 $body .= $this->textLine('--' . $this->boundary[2]);
@@ -2645,7 +2762,12 @@ class PHPMailer
                 $body .= $this->textLine(' boundary="' . $this->boundary[3] . '";');
                 $body .= $this->textLine(' type="' . static::CONTENT_TYPE_TEXT_HTML . '"');
                 $body .= static::$LE;
-                $body .= $this->getBoundary($this->boundary[3], $bodyCharSet, static::CONTENT_TYPE_TEXT_HTML, $bodyEncoding);
+                $body .= $this->getBoundary(
+                    $this->boundary[3],
+                    $bodyCharSet,
+                    static::CONTENT_TYPE_TEXT_HTML,
+                    $bodyEncoding
+                );
                 $body .= $this->encodeString($this->Body, $bodyEncoding);
                 $body .= static::$LE;
                 $body .= $this->attachAll('inline', $this->boundary[3]);
@@ -2672,9 +2794,10 @@ class PHPMailer
                 if (!defined('PKCS7_TEXT')) {
                     throw new Exception($this->lang('extension_missing') . 'openssl');
                 }
-                $file = fopen('php://temp', 'rb+');
-                $signed = fopen('php://temp', 'rb+');
-                fwrite($file, $body);
+
+                $file = tempnam(sys_get_temp_dir(), 'srcsign');
+                $signed = tempnam(sys_get_temp_dir(), 'mailsign');
+                file_put_contents($file, $body);
 
                 //Workaround for PHP bug https://bugs.php.net/bug.php?id=69197
                 if (empty($this->sign_extracerts_file)) {
@@ -2696,16 +2819,17 @@ class PHPMailer
                         $this->sign_extracerts_file
                     );
                 }
-                fclose($file);
+
+                @unlink($file);
                 if ($sign) {
                     $body = file_get_contents($signed);
-                    fclose($signed);
+                    @unlink($signed);
                     //The message returned by openssl contains both headers and body, so need to split them up
                     $parts = explode("\n\n", $body, 2);
                     $this->MIMEHeader .= $parts[0] . static::$LE . static::$LE;
                     $body = $parts[1];
                 } else {
-                    fclose($signed);
+                    @unlink($signed);
                     throw new Exception($this->lang('signing') . openssl_error_string());
                 }
             } catch (Exception $exc) {
@@ -2732,20 +2856,20 @@ class PHPMailer
     protected function getBoundary($boundary, $charSet, $contentType, $encoding)
     {
         $result = '';
-        if ('' == $charSet) {
+        if ('' === $charSet) {
             $charSet = $this->CharSet;
         }
-        if ('' == $contentType) {
+        if ('' === $contentType) {
             $contentType = $this->ContentType;
         }
-        if ('' == $encoding) {
+        if ('' === $encoding) {
             $encoding = $this->Encoding;
         }
         $result .= $this->textLine('--' . $boundary);
         $result .= sprintf('Content-Type: %s; charset=%s', $contentType, $charSet);
         $result .= static::$LE;
         // RFC1341 part 5 says 7bit is assumed if not specified
-        if (static::ENCODING_7BIT != $encoding) {
+        if (static::ENCODING_7BIT !== $encoding) {
             $result .= $this->headerLine('Content-Transfer-Encoding', $encoding);
         }
         $result .= static::$LE;
@@ -2782,7 +2906,7 @@ class PHPMailer
             $type[] = 'attach';
         }
         $this->message_type = implode('_', $type);
-        if ('' == $this->message_type) {
+        if ('' === $this->message_type) {
             //The 'plain' message_type refers to the message having a single body element, not that it is plain-text
             $this->message_type = 'plain';
         }
@@ -2838,17 +2962,17 @@ class PHPMailer
         $disposition = 'attachment'
     ) {
         try {
-            if (!static::isPermittedPath($path) || !@is_file($path)) {
+            if (!static::isPermittedPath($path) || !@is_file($path) || !is_readable($path)) {
                 throw new Exception($this->lang('file_access') . $path, self::STOP_CONTINUE);
             }
 
             // If a MIME type is not specified, try to work it out from the file name
-            if ('' == $type) {
+            if ('' === $type) {
                 $type = static::filenameToType($path);
             }
 
-            $filename = static::mb_pathinfo($path, PATHINFO_BASENAME);
-            if ('' == $name) {
+            $filename = (string) static::mb_pathinfo($path, PATHINFO_BASENAME);
+            if ('' === $name) {
                 $name = $filename;
             }
 
@@ -2896,6 +3020,8 @@ class PHPMailer
      * @param string $disposition_type
      * @param string $boundary
      *
+     * @throws Exception
+     *
      * @return string
      */
     protected function attachAll($disposition_type, $boundary)
@@ -2908,7 +3034,7 @@ class PHPMailer
         // Add all attachments
         foreach ($this->attachment as $attachment) {
             // Check if it is a valid disposition_filter
-            if ($attachment[6] == $disposition_type) {
+            if ($attachment[6] === $disposition_type) {
                 // Check for string attachment
                 $string = '';
                 $path = '';
@@ -2920,7 +3046,7 @@ class PHPMailer
                 }
 
                 $inclhash = hash('sha256', serialize($attachment));
-                if (in_array($inclhash, $incl)) {
+                if (in_array($inclhash, $incl, true)) {
                     continue;
                 }
                 $incl[] = $inclhash;
@@ -2929,7 +3055,7 @@ class PHPMailer
                 $type = $attachment[4];
                 $disposition = $attachment[6];
                 $cid = $attachment[7];
-                if ('inline' == $disposition and array_key_exists($cid, $cidUniq)) {
+                if ('inline' === $disposition && array_key_exists($cid, $cidUniq)) {
                     continue;
                 }
                 $cidUniq[$cid] = true;
@@ -2951,16 +3077,13 @@ class PHPMailer
                     );
                 }
                 // RFC1341 part 5 says 7bit is assumed if not specified
-                if (static::ENCODING_7BIT != $encoding) {
+                if (static::ENCODING_7BIT !== $encoding) {
                     $mime[] = sprintf('Content-Transfer-Encoding: %s%s', $encoding, static::$LE);
                 }
 
-                if (!empty($cid)) {
-                    $mime[] = sprintf(
-                        'Content-ID: <%s>%s',
-                        $this->encodeHeader($this->secureHeader($cid)),
-                        static::$LE
-                    );
+                //Only set Content-IDs on inline attachments
+                if ((string) $cid !== '' && $disposition === 'inline') {
+                    $mime[] = 'Content-ID: <' . $this->encodeHeader($this->secureHeader($cid)) . '>' . static::$LE;
                 }
 
                 // If a filename contains any of these chars, it should be quoted,
@@ -2969,28 +3092,26 @@ class PHPMailer
                 // Allow for bypassing the Content-Disposition header totally
                 if (!empty($disposition)) {
                     $encoded_name = $this->encodeHeader($this->secureHeader($name));
-                    if (preg_match('/[ \(\)<>@,;:\\"\/\[\]\?=]/', $encoded_name)) {
+                    if (preg_match('/[ ()<>@,;:"\/\[\]?=]/', $encoded_name)) {
                         $mime[] = sprintf(
                             'Content-Disposition: %s; filename="%s"%s',
                             $disposition,
                             $encoded_name,
                             static::$LE . static::$LE
                         );
+                    } elseif (!empty($encoded_name)) {
+                        $mime[] = sprintf(
+                            'Content-Disposition: %s; filename=%s%s',
+                            $disposition,
+                            $encoded_name,
+                            static::$LE . static::$LE
+                        );
                     } else {
-                        if (!empty($encoded_name)) {
-                            $mime[] = sprintf(
-                                'Content-Disposition: %s; filename=%s%s',
-                                $disposition,
-                                $encoded_name,
-                                static::$LE . static::$LE
-                            );
-                        } else {
-                            $mime[] = sprintf(
-                                'Content-Disposition: %s%s',
-                                $disposition,
-                                static::$LE . static::$LE
-                            );
-                        }
+                        $mime[] = sprintf(
+                            'Content-Disposition: %s%s',
+                            $disposition,
+                            static::$LE . static::$LE
+                        );
                     }
                 } else {
                     $mime[] = static::$LE;
@@ -3021,14 +3142,12 @@ class PHPMailer
      * @param string $path     The full path to the file
      * @param string $encoding The encoding to use; one of 'base64', '7bit', '8bit', 'binary', 'quoted-printable'
      *
-     * @throws Exception
-     *
      * @return string
      */
     protected function encodeFile($path, $encoding = self::ENCODING_BASE64)
     {
         try {
-            if (!static::isPermittedPath($path) || !file_exists($path)) {
+            if (!static::isPermittedPath($path) || !file_exists($path) || !is_readable($path)) {
                 throw new Exception($this->lang('file_open') . $path, self::STOP_CONTINUE);
             }
             $file_buffer = file_get_contents($path);
@@ -3040,7 +3159,10 @@ class PHPMailer
             return $file_buffer;
         } catch (Exception $exc) {
             $this->setError($exc->getMessage());
-
+            $this->edebug($exc->getMessage());
+            if ($this->exceptions) {
+                throw $exc;
+            }
             return '';
         }
     }
@@ -3071,7 +3193,7 @@ class PHPMailer
             case static::ENCODING_8BIT:
                 $encoded = static::normalizeBreaks($str);
                 // Make sure it ends with a line break
-                if (substr($encoded, -(strlen(static::$LE))) != static::$LE) {
+                if (substr($encoded, -(strlen(static::$LE))) !== static::$LE) {
                     $encoded .= static::$LE;
                 }
                 break;
@@ -3110,7 +3232,7 @@ class PHPMailer
                 if (!preg_match('/[\200-\377]/', $str)) {
                     // Can't use addslashes as we don't know the value of magic_quotes_sybase
                     $encoded = addcslashes($str, "\0..\37\177\\\"");
-                    if (($str == $encoded) and !preg_match('/[^A-Za-z0-9!#$%&\'*+\/=?^_`{|}~ -]/', $str)) {
+                    if (($str === $encoded) && !preg_match('/[^A-Za-z0-9!#$%&\'*+\/=?^_`{|}~ -]/', $str)) {
                         return $encoded;
                     }
 
@@ -3128,51 +3250,57 @@ class PHPMailer
                 break;
         }
 
-        //RFCs specify a maximum line length of 78 chars, however mail() will sometimes
-        //corrupt messages with headers longer than 65 chars. See #818
-        $lengthsub = 'mail' == $this->Mailer ? 13 : 0;
-        $maxlen = static::STD_LINE_LENGTH - $lengthsub;
-        // Try to select the encoding which should produce the shortest output
-        if ($matchcount > strlen($str) / 3) {
-            // More than a third of the content will need encoding, so B encoding will be most efficient
-            $encoding = 'B';
-            //This calculation is:
-            // max line length
-            // - shorten to avoid mail() corruption
-            // - Q/B encoding char overhead ("` =?<charset>?[QB]?<content>?=`")
-            // - charset name length
-            $maxlen = static::STD_LINE_LENGTH - $lengthsub - 8 - strlen($this->CharSet);
-            if ($this->hasMultiBytes($str)) {
-                // Use a custom function which correctly encodes and wraps long
-                // multibyte strings without breaking lines within a character
-                $encoded = $this->base64EncodeWrapMB($str, "\n");
-            } else {
-                $encoded = base64_encode($str);
-                $maxlen -= $maxlen % 4;
-                $encoded = trim(chunk_split($encoded, $maxlen, "\n"));
-            }
-            $encoded = preg_replace('/^(.*)$/m', ' =?' . $this->CharSet . "?$encoding?\\1?=", $encoded);
-        } elseif ($matchcount > 0) {
-            //1 or more chars need encoding, use Q-encode
-            $encoding = 'Q';
-            //Recalc max line length for Q encoding - see comments on B encode
-            $maxlen = static::STD_LINE_LENGTH - $lengthsub - 8 - strlen($this->CharSet);
-            $encoded = $this->encodeQ($str, $position);
-            $encoded = $this->wrapText($encoded, $maxlen, true);
-            $encoded = str_replace('=' . static::$LE, "\n", trim($encoded));
-            $encoded = preg_replace('/^(.*)$/m', ' =?' . $this->CharSet . "?$encoding?\\1?=", $encoded);
-        } elseif (strlen($str) > $maxlen) {
-            //No chars need encoding, but line is too long, so fold it
-            $encoded = trim($this->wrapText($str, $maxlen, false));
-            if ($str == $encoded) {
-                //Wrapping nicely didn't work, wrap hard instead
-                $encoded = trim(chunk_split($str, static::STD_LINE_LENGTH, static::$LE));
-            }
-            $encoded = str_replace(static::$LE, "\n", trim($encoded));
-            $encoded = preg_replace('/^(.*)$/m', ' \\1', $encoded);
+        if ($this->has8bitChars($str)) {
+            $charset = $this->CharSet;
         } else {
-            //No reformatting needed
-            return $str;
+            $charset = static::CHARSET_ASCII;
+        }
+
+        // Q/B encoding adds 8 chars and the charset ("` =?<charset>?[QB]?<content>?=`").
+        $overhead = 8 + strlen($charset);
+
+        if ('mail' === $this->Mailer) {
+            $maxlen = static::MAIL_MAX_LINE_LENGTH - $overhead;
+        } else {
+            $maxlen = static::MAX_LINE_LENGTH - $overhead;
+        }
+
+        // Select the encoding that produces the shortest output and/or prevents corruption.
+        if ($matchcount > strlen($str) / 3) {
+            // More than 1/3 of the content needs encoding, use B-encode.
+            $encoding = 'B';
+        } elseif ($matchcount > 0) {
+            // Less than 1/3 of the content needs encoding, use Q-encode.
+            $encoding = 'Q';
+        } elseif (strlen($str) > $maxlen) {
+            // No encoding needed, but value exceeds max line length, use Q-encode to prevent corruption.
+            $encoding = 'Q';
+        } else {
+            // No reformatting needed
+            $encoding = false;
+        }
+
+        switch ($encoding) {
+            case 'B':
+                if ($this->hasMultiBytes($str)) {
+                    // Use a custom function which correctly encodes and wraps long
+                    // multibyte strings without breaking lines within a character
+                    $encoded = $this->base64EncodeWrapMB($str, "\n");
+                } else {
+                    $encoded = base64_encode($str);
+                    $maxlen -= $maxlen % 4;
+                    $encoded = trim(chunk_split($encoded, $maxlen, "\n"));
+                }
+                $encoded = preg_replace('/^(.*)$/m', ' =?' . $charset . "?$encoding?\\1?=", $encoded);
+                break;
+            case 'Q':
+                $encoded = $this->encodeQ($str, $position);
+                $encoded = $this->wrapText($encoded, $maxlen, true);
+                $encoded = str_replace('=' . static::$LE, "\n", trim($encoded));
+                $encoded = preg_replace('/^(.*)$/m', ' =?' . $charset . "?$encoding?\\1?=", $encoded);
+                break;
+            default:
+                return $str;
         }
 
         return trim(static::normalizeBreaks($encoded));
@@ -3236,6 +3364,7 @@ class PHPMailer
         // Base64 has a 4:3 ratio
         $avgLength = floor($length * $ratio * .75);
 
+        $offset = 0;
         for ($i = 0; $i < $mb_length; $i += $offset) {
             $lookBack = 0;
             do {
@@ -3296,7 +3425,6 @@ class PHPMailer
             default:
                 // RFC 2047 section 5.1
                 // Replace every high ascii, control, =, ? and _ characters
-                /** @noinspection SuspiciousAssignmentsInspection */
                 $pattern = '\000-\011\013\014\016-\037\075\077\137\177-\377' . $pattern;
                 break;
         }
@@ -3304,7 +3432,7 @@ class PHPMailer
         if (preg_match_all("/[{$pattern}]/", $encoded, $matches)) {
             // If the string contains an '=', make sure it's the first thing we replace
             // so as to avoid double-encoding
-            $eqkey = array_search('=', $matches[0]);
+            $eqkey = array_search('=', $matches[0], true);
             if (false !== $eqkey) {
                 unset($matches[0][$eqkey]);
                 array_unshift($matches[0], '=');
@@ -3342,7 +3470,7 @@ class PHPMailer
     ) {
         try {
             // If a MIME type is not specified, try to work it out from the file name
-            if ('' == $type) {
+            if ('' === $type) {
                 $type = static::filenameToType($filename);
             }
 
@@ -3354,7 +3482,7 @@ class PHPMailer
             $this->attachment[] = [
                 0 => $string,
                 1 => $filename,
-                2 => static::mb_pathinfo($filename, PATHINFO_EXTENSION),
+                2 => static::mb_pathinfo($filename, PATHINFO_BASENAME),
                 3 => $encoding,
                 4 => $type,
                 5 => true, // isStringAttachment
@@ -3404,12 +3532,12 @@ class PHPMailer
         $disposition = 'inline'
     ) {
         try {
-            if (!static::isPermittedPath($path) || !@is_file($path)) {
+            if (!static::isPermittedPath($path) || !@is_file($path) || !is_readable($path)) {
                 throw new Exception($this->lang('file_access') . $path, self::STOP_CONTINUE);
             }
 
             // If a MIME type is not specified, try to work it out from the file name
-            if ('' == $type) {
+            if ('' === $type) {
                 $type = static::filenameToType($path);
             }
 
@@ -3417,8 +3545,8 @@ class PHPMailer
                 throw new Exception($this->lang('encoding') . $encoding);
             }
 
-            $filename = static::mb_pathinfo($path, PATHINFO_BASENAME);
-            if ('' == $name) {
+            $filename = (string) static::mb_pathinfo($path, PATHINFO_BASENAME);
+            if ('' === $name) {
                 $name = $filename;
             }
 
@@ -3475,7 +3603,7 @@ class PHPMailer
     ) {
         try {
             // If a MIME type is not specified, try to work it out from the name
-            if ('' == $type and !empty($name)) {
+            if ('' === $type && !empty($name)) {
                 $type = static::filenameToType($name);
             }
 
@@ -3510,7 +3638,7 @@ class PHPMailer
     /**
      * Validate encodings.
      *
-     * @param $encoding
+     * @param string $encoding
      *
      * @return bool
      */
@@ -3539,7 +3667,7 @@ class PHPMailer
     protected function cidExists($cid)
     {
         foreach ($this->attachment as $attachment) {
-            if ('inline' == $attachment[6] and $cid == $attachment[7]) {
+            if ('inline' === $attachment[6] && $cid === $attachment[7]) {
                 return true;
             }
         }
@@ -3555,7 +3683,7 @@ class PHPMailer
     public function inlineImageExists()
     {
         foreach ($this->attachment as $attachment) {
-            if ('inline' == $attachment[6]) {
+            if ('inline' === $attachment[6]) {
                 return true;
             }
         }
@@ -3571,7 +3699,7 @@ class PHPMailer
     public function attachmentExists()
     {
         foreach ($this->attachment as $attachment) {
-            if ('attachment' == $attachment[6]) {
+            if ('attachment' === $attachment[6]) {
                 return true;
             }
         }
@@ -3598,8 +3726,8 @@ class PHPMailer
     {
         $this->RecipientsQueue = array_filter(
             $this->RecipientsQueue,
-            function ($params) use ($kind) {
-                return $params[0] != $kind;
+            static function ($params) use ($kind) {
+                return $params[0] !== $kind;
             }
         );
     }
@@ -3685,7 +3813,7 @@ class PHPMailer
     protected function setError($msg)
     {
         ++$this->error_count;
-        if ('smtp' == $this->Mailer and null !== $this->smtp) {
+        if ('smtp' === $this->Mailer && null !== $this->smtp) {
             $lasterror = $this->smtp->getError();
             if (!empty($lasterror['error'])) {
                 $msg .= $this->lang('smtp_error') . $lasterror['error'];
@@ -3728,9 +3856,9 @@ class PHPMailer
         $result = '';
         if (!empty($this->Hostname)) {
             $result = $this->Hostname;
-        } elseif (isset($_SERVER) and array_key_exists('SERVER_NAME', $_SERVER)) {
+        } elseif (isset($_SERVER) && array_key_exists('SERVER_NAME', $_SERVER)) {
             $result = $_SERVER['SERVER_NAME'];
-        } elseif (function_exists('gethostname') and gethostname() !== false) {
+        } elseif (function_exists('gethostname') && gethostname() !== false) {
             $result = gethostname();
         } elseif (php_uname('n') !== false) {
             $result = php_uname('n');
@@ -3754,22 +3882,23 @@ class PHPMailer
     {
         //Simple syntax limits
         if (empty($host)
-            or !is_string($host)
-            or strlen($host) > 256
+            || !is_string($host)
+            || strlen($host) > 256
+            || !preg_match('/^([a-zA-Z\d.-]*|\[[a-fA-F\d:]+])$/', $host)
         ) {
             return false;
         }
         //Looks like a bracketed IPv6 address
-        if (trim($host, '[]') != $host) {
-            return (bool) filter_var(trim($host, '[]'), FILTER_VALIDATE_IP, FILTER_FLAG_IPV6);
+        if (strlen($host) > 2 && substr($host, 0, 1) === '[' && substr($host, -1, 1) === ']') {
+            return filter_var(substr($host, 1, -1), FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) !== false;
         }
         //If removing all the dots results in a numeric string, it must be an IPv4 address.
         //Need to check this first because otherwise things like `999.0.0.0` are considered valid host names
         if (is_numeric(str_replace('.', '', $host))) {
             //Is it a valid IPv4 address?
-            return (bool) filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);
+            return filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false;
         }
-        if (filter_var('http://' . $host, FILTER_VALIDATE_URL)) {
+        if (filter_var('http://' . $host, FILTER_VALIDATE_URL) !== false) {
             //Is it a syntactically valid hostname?
             return true;
         }
@@ -3787,11 +3916,11 @@ class PHPMailer
     protected function lang($key)
     {
         if (count($this->language) < 1) {
-            $this->setLanguage('en'); // set the default language
+            $this->setLanguage(); // set the default language
         }
 
         if (array_key_exists($key, $this->language)) {
-            if ('smtp_connect_failed' == $key) {
+            if ('smtp_connect_failed' === $key) {
                 //Include a link to troubleshooting docs on SMTP connection failure
                 //this is by far the biggest cause of support questions
                 //but it's usually not PHPMailer's fault.
@@ -3822,15 +3951,28 @@ class PHPMailer
      *
      * @param string      $name  Custom header name
      * @param string|null $value Header value
+     *
+     * @throws Exception
      */
     public function addCustomHeader($name, $value = null)
     {
-        if (null === $value) {
+        if (null === $value && strpos($name, ':') !== false) {
             // Value passed in as name:value
-            $this->CustomHeader[] = explode(':', $name, 2);
-        } else {
-            $this->CustomHeader[] = [$name, $value];
+            list($name, $value) = explode(':', $name, 2);
         }
+        $name = trim($name);
+        $value = trim($value);
+        //Ensure name is not empty, and that neither name nor value contain line breaks
+        if (empty($name) || strpbrk($name . $value, "\r\n") !== false) {
+            if ($this->exceptions) {
+                throw new Exception('Invalid header name or value');
+            }
+
+            return false;
+        }
+        $this->CustomHeader[] = [$name, $value];
+
+        return true;
     }
 
     /**
@@ -3857,36 +3999,45 @@ class PHPMailer
      * @param string        $message  HTML message string
      * @param string        $basedir  Absolute path to a base directory to prepend to relative paths to images
      * @param bool|callable $advanced Whether to use the internal HTML to text converter
-     *                                or your own custom converter @see PHPMailer::html2text()
+     *                                or your own custom converter @return string $message The transformed message Body
      *
-     * @return string $message The transformed message Body
+     * @throws Exception
+     *
+     * @see PHPMailer::html2text()
      */
     public function msgHTML($message, $basedir = '', $advanced = false)
     {
-        preg_match_all('/(src|background)=["\'](.*)["\']/Ui', $message, $images);
+        preg_match_all('/(?<!-)(src|background)=["\'](.*)["\']/Ui', $message, $images);
         if (array_key_exists(2, $images)) {
-            if (strlen($basedir) > 1 && '/' != substr($basedir, -1)) {
+            if (strlen($basedir) > 1 && '/' !== substr($basedir, -1)) {
                 // Ensure $basedir has a trailing /
                 $basedir .= '/';
             }
             foreach ($images[2] as $imgindex => $url) {
                 // Convert data URIs into embedded images
                 //e.g. "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
+                $match = [];
                 if (preg_match('#^data:(image/(?:jpe?g|gif|png));?(base64)?,(.+)#', $url, $match)) {
-                    if (count($match) == 4 and static::ENCODING_BASE64 == $match[2]) {
+                    if (count($match) === 4 && static::ENCODING_BASE64 === $match[2]) {
                         $data = base64_decode($match[3]);
-                    } elseif ('' == $match[2]) {
+                    } elseif ('' === $match[2]) {
                         $data = rawurldecode($match[3]);
                     } else {
                         //Not recognised so leave it alone
                         continue;
                     }
-                    //Hash the decoded data, not the URL so that the same data-URI image used in multiple places
+                    //Hash the decoded data, not the URL, so that the same data-URI image used in multiple places
                     //will only be embedded once, even if it used a different encoding
-                    $cid = hash('sha256', $data) . '@phpmailer.0'; // RFC2392 S 2
+                    $cid = substr(hash('sha256', $data), 0, 32) . '@phpmailer.0'; // RFC2392 S 2
 
                     if (!$this->cidExists($cid)) {
-                        $this->addStringEmbeddedImage($data, $cid, 'embed' . $imgindex, static::ENCODING_BASE64, $match[1]);
+                        $this->addStringEmbeddedImage(
+                            $data,
+                            $cid,
+                            'embed' . $imgindex,
+                            static::ENCODING_BASE64,
+                            $match[1]
+                        );
                     }
                     $message = str_replace(
                         $images[0][$imgindex],
@@ -3898,22 +4049,23 @@ class PHPMailer
                 if (// Only process relative URLs if a basedir is provided (i.e. no absolute local paths)
                     !empty($basedir)
                     // Ignore URLs containing parent dir traversal (..)
-                    and (strpos($url, '..') === false)
+                    && (strpos($url, '..') === false)
                     // Do not change urls that are already inline images
-                    and 0 !== strpos($url, 'cid:')
+                    && 0 !== strpos($url, 'cid:')
                     // Do not change absolute URLs, including anonymous protocol
-                    and !preg_match('#^[a-z][a-z0-9+.-]*:?//#i', $url)
+                    && !preg_match('#^[a-z][a-z0-9+.-]*:?//#i', $url)
                 ) {
                     $filename = static::mb_pathinfo($url, PATHINFO_BASENAME);
                     $directory = dirname($url);
-                    if ('.' == $directory) {
+                    if ('.' === $directory) {
                         $directory = '';
                     }
-                    $cid = hash('sha256', $url) . '@phpmailer.0'; // RFC2392 S 2
-                    if (strlen($basedir) > 1 and '/' != substr($basedir, -1)) {
+                    // RFC2392 S 2
+                    $cid = substr(hash('sha256', $url), 0, 32) . '@phpmailer.0';
+                    if (strlen($basedir) > 1 && '/' !== substr($basedir, -1)) {
                         $basedir .= '/';
                     }
-                    if (strlen($directory) > 1 and '/' != substr($directory, -1)) {
+                    if (strlen($directory) > 1 && '/' !== substr($directory, -1)) {
                         $directory .= '/';
                     }
                     if ($this->addEmbeddedImage(
@@ -3933,7 +4085,7 @@ class PHPMailer
                 }
             }
         }
-        $this->isHTML(true);
+        $this->isHTML();
         // Convert all message body line breaks to LE, makes quoted-printable encoding work much better
         $this->Body = static::normalizeBreaks($message);
         $this->AltBody = static::normalizeBreaks($this->html2text($message, $advanced));
@@ -3971,7 +4123,7 @@ class PHPMailer
     public function html2text($html, $advanced = false)
     {
         if (is_callable($advanced)) {
-            return call_user_func($advanced, $html);
+            return $advanced($html);
         }
 
         return html_entity_decode(
@@ -4135,7 +4287,7 @@ class PHPMailer
      * Multi-byte-safe pathinfo replacement.
      * Drop-in replacement for pathinfo(), but multibyte- and cross-platform-safe.
      *
-     * @see    http://www.php.net/manual/en/function.pathinfo.php#107461
+     * @see http://www.php.net/manual/en/function.pathinfo.php#107461
      *
      * @param string     $path    A filename or path, does not need to exist as a file
      * @param int|string $options Either a PATHINFO_* constant,
@@ -4184,9 +4336,9 @@ class PHPMailer
      * You should avoid this function - it's more verbose, less efficient, more error-prone and
      * harder to debug than setting properties directly.
      * Usage Example:
-     * `$mail->set('SMTPSecure', 'tls');`
+     * `$mail->set('SMTPSecure', static::ENCRYPTION_STARTTLS);`
      *   is the same as:
-     * `$mail->SMTPSecure = 'tls';`.
+     * `$mail->SMTPSecure = static::ENCRYPTION_STARTTLS;`.
      *
      * @param string $name  The property name to set
      * @param mixed  $value The value to set the property to
@@ -4233,7 +4385,7 @@ class PHPMailer
             $breaktype = static::$LE;
         }
         // Normalise to \n
-        $text = str_replace(["\r\n", "\r"], "\n", $text);
+        $text = str_replace([self::CRLF, "\r"], "\n", $text);
         // Now convert LE as needed
         if ("\n" !== $breaktype) {
             $text = str_replace("\n", $breaktype, $text);
@@ -4242,6 +4394,18 @@ class PHPMailer
         return $text;
     }
 
+    /**
+     * Remove trailing breaks from a string.
+     *
+     * @param string $text
+     *
+     * @return string The text to remove breaks from
+     */
+    public static function stripTrailingWSP($text)
+    {
+        return rtrim($text, " \r\n\t");
+    }
+
     /**
      * Return the current line break format string.
      *
@@ -4291,7 +4455,7 @@ class PHPMailer
         $len = strlen($txt);
         for ($i = 0; $i < $len; ++$i) {
             $ord = ord($txt[$i]);
-            if (((0x21 <= $ord) and ($ord <= 0x3A)) or $ord == 0x3C or ((0x3E <= $ord) and ($ord <= 0x7E))) {
+            if (((0x21 <= $ord) && ($ord <= 0x3A)) || $ord === 0x3C || ((0x3E <= $ord) && ($ord <= 0x7E))) {
                 $line .= $txt[$i];
             } else {
                 $line .= '=' . sprintf('%02X', $ord);
@@ -4322,7 +4486,7 @@ class PHPMailer
         $privKeyStr = !empty($this->DKIM_private_string) ?
             $this->DKIM_private_string :
             file_get_contents($this->DKIM_private);
-        if ('' != $this->DKIM_passphrase) {
+        if ('' !== $this->DKIM_passphrase) {
             $privKey = openssl_pkey_get_private($privKeyStr, $this->DKIM_passphrase);
         } else {
             $privKey = openssl_pkey_get_private($privKeyStr);
@@ -4342,7 +4506,7 @@ class PHPMailer
      * Uses the 'relaxed' algorithm from RFC6376 section 3.4.2.
      * Canonicalized headers should *always* use CRLF, regardless of mailer setting.
      *
-     * @see    https://tools.ietf.org/html/rfc6376#section-3.4.2
+     * @see https://tools.ietf.org/html/rfc6376#section-3.4.2
      *
      * @param string $signHeader Header
      *
@@ -4350,13 +4514,15 @@ class PHPMailer
      */
     public function DKIM_HeaderC($signHeader)
     {
-        //Unfold all header continuation lines
-        //Also collapses folded whitespace.
+        //Normalize breaks to CRLF (regardless of the mailer)
+        $signHeader = static::normalizeBreaks($signHeader, self::CRLF);
+        //Unfold header lines
         //Note PCRE \s is too broad a definition of whitespace; RFC5322 defines it as `[ \t]`
         //@see https://tools.ietf.org/html/rfc5322#section-2.2
         //That means this may break if you do something daft like put vertical tabs in your headers.
         $signHeader = preg_replace('/\r\n[ \t]+/', ' ', $signHeader);
-        $lines = explode("\r\n", $signHeader);
+        //Break headers out into an array
+        $lines = explode(self::CRLF, $signHeader);
         foreach ($lines as $key => $line) {
             //If the header is missing a :, skip it as it's invalid
             //This is likely to happen because the explode() above will also split
@@ -4367,16 +4533,16 @@ class PHPMailer
             list($heading, $value) = explode(':', $line, 2);
             //Lower-case header name
             $heading = strtolower($heading);
-            //Collapse white space within the value
-            $value = preg_replace('/[ \t]{2,}/', ' ', $value);
+            //Collapse white space within the value, also convert WSP to space
+            $value = preg_replace('/[ \t]+/', ' ', $value);
             //RFC6376 is slightly unclear here - it says to delete space at the *end* of each value
             //But then says to delete space before and after the colon.
             //Net result is the same as trimming both ends of the value.
-            //by elimination, the same applies to the field name
+            //By elimination, the same applies to the field name
             $lines[$key] = trim($heading, " \t") . ':' . trim($value, " \t");
         }
 
-        return implode("\r\n", $lines);
+        return implode(self::CRLF, $lines);
     }
 
     /**
@@ -4384,7 +4550,7 @@ class PHPMailer
      * Uses the 'simple' algorithm from RFC6376 section 3.4.3.
      * Canonicalized bodies should *always* use CRLF, regardless of mailer setting.
      *
-     * @see    https://tools.ietf.org/html/rfc6376#section-3.4.3
+     * @see https://tools.ietf.org/html/rfc6376#section-3.4.3
      *
      * @param string $body Message Body
      *
@@ -4393,13 +4559,13 @@ class PHPMailer
     public function DKIM_BodyC($body)
     {
         if (empty($body)) {
-            return "\r\n";
+            return self::CRLF;
         }
         // Normalize line endings to CRLF
-        $body = static::normalizeBreaks($body, "\r\n");
+        $body = static::normalizeBreaks($body, self::CRLF);
 
         //Reduce multiple trailing line breaks to a single one
-        return rtrim($body, "\r\n") . "\r\n";
+        return static::stripTrailingWSP($body) . self::CRLF;
     }
 
     /**
@@ -4409,109 +4575,143 @@ class PHPMailer
      * @param string $subject      Subject
      * @param string $body         Body
      *
+     * @throws Exception
+     *
      * @return string
      */
     public function DKIM_Add($headers_line, $subject, $body)
     {
         $DKIMsignatureType = 'rsa-sha256'; // Signature & hash algorithms
-        $DKIMcanonicalization = 'relaxed/simple'; // Canonicalization of header/body
+        $DKIMcanonicalization = 'relaxed/simple'; // Canonicalization methods of header & body
         $DKIMquery = 'dns/txt'; // Query method
-        $DKIMtime = time(); // Signature Timestamp = seconds since 00:00:00 - Jan 1, 1970 (UTC time zone)
-        $subject_header = "Subject: $subject";
-        $headers = explode(static::$LE, $headers_line);
-        $from_header = '';
-        $to_header = '';
-        $date_header = '';
-        $current = '';
-        $copiedHeaderFields = '';
-        $foundExtraHeaders = [];
-        $extraHeaderKeys = '';
-        $extraHeaderValues = '';
-        $extraCopyHeaderFields = '';
-        foreach ($headers as $header) {
-            if (strpos($header, 'From:') === 0) {
-                $from_header = $header;
-                $current = 'from_header';
-            } elseif (strpos($header, 'To:') === 0) {
-                $to_header = $header;
-                $current = 'to_header';
-            } elseif (strpos($header, 'Date:') === 0) {
-                $date_header = $header;
-                $current = 'date_header';
-            } elseif (!empty($this->DKIM_extraHeaders)) {
-                foreach ($this->DKIM_extraHeaders as $extraHeader) {
-                    if (strpos($header, $extraHeader . ':') === 0) {
-                        $headerValue = $header;
-                        foreach ($this->CustomHeader as $customHeader) {
-                            if ($customHeader[0] === $extraHeader) {
-                                $headerValue = trim($customHeader[0]) .
-                                               ': ' .
-                                               $this->encodeHeader(trim($customHeader[1]));
-                                break;
-                            }
+        $DKIMtime = time();
+        //Always sign these headers without being asked
+        //Recommended list from https://tools.ietf.org/html/rfc6376#section-5.4.1
+        $autoSignHeaders = [
+            'from',
+            'to',
+            'cc',
+            'date',
+            'subject',
+            'reply-to',
+            'message-id',
+            'content-type',
+            'mime-version',
+            'x-mailer',
+        ];
+        if (stripos($headers_line, 'Subject') === false) {
+            $headers_line .= 'Subject: ' . $subject . static::$LE;
+        }
+        $headerLines = explode(static::$LE, $headers_line);
+        $currentHeaderLabel = '';
+        $currentHeaderValue = '';
+        $parsedHeaders = [];
+        $headerLineIndex = 0;
+        $headerLineCount = count($headerLines);
+        foreach ($headerLines as $headerLine) {
+            $matches = [];
+            if (preg_match('/^([^ \t]*?)(?::[ \t]*)(.*)$/', $headerLine, $matches)) {
+                if ($currentHeaderLabel !== '') {
+                    //We were previously in another header; This is the start of a new header, so save the previous one
+                    $parsedHeaders[] = ['label' => $currentHeaderLabel, 'value' => $currentHeaderValue];
+                }
+                $currentHeaderLabel = $matches[1];
+                $currentHeaderValue = $matches[2];
+            } elseif (preg_match('/^[ \t]+(.*)$/', $headerLine, $matches)) {
+                //This is a folded continuation of the current header, so unfold it
+                $currentHeaderValue .= ' ' . $matches[1];
+            }
+            ++$headerLineIndex;
+            if ($headerLineIndex >= $headerLineCount) {
+                //This was the last line, so finish off this header
+                $parsedHeaders[] = ['label' => $currentHeaderLabel, 'value' => $currentHeaderValue];
+            }
+        }
+        $copiedHeaders = [];
+        $headersToSignKeys = [];
+        $headersToSign = [];
+        foreach ($parsedHeaders as $header) {
+            //Is this header one that must be included in the DKIM signature?
+            if (in_array(strtolower($header['label']), $autoSignHeaders, true)) {
+                $headersToSignKeys[] = $header['label'];
+                $headersToSign[] = $header['label'] . ': ' . $header['value'];
+                if ($this->DKIM_copyHeaderFields) {
+                    $copiedHeaders[] = $header['label'] . ':' . //Note no space after this, as per RFC
+                        str_replace('|', '=7C', $this->DKIM_QP($header['value']));
+                }
+                continue;
+            }
+            //Is this an extra custom header we've been asked to sign?
+            if (in_array($header['label'], $this->DKIM_extraHeaders, true)) {
+                //Find its value in custom headers
+                foreach ($this->CustomHeader as $customHeader) {
+                    if ($customHeader[0] === $header['label']) {
+                        $headersToSignKeys[] = $header['label'];
+                        $headersToSign[] = $header['label'] . ': ' . $header['value'];
+                        if ($this->DKIM_copyHeaderFields) {
+                            $copiedHeaders[] = $header['label'] . ':' . //Note no space after this, as per RFC
+                                str_replace('|', '=7C', $this->DKIM_QP($header['value']));
                         }
-                        $foundExtraHeaders[$extraHeader] = $headerValue;
-                        $current = '';
-                        break;
+                        //Skip straight to the next header
+                        continue 2;
                     }
                 }
-            } else {
-                if (!empty($$current) and strpos($header, ' =?') === 0) {
-                    $$current .= $header;
-                } else {
-                    $current = '';
+            }
+        }
+        $copiedHeaderFields = '';
+        if ($this->DKIM_copyHeaderFields && count($copiedHeaders) > 0) {
+            //Assemble a DKIM 'z' tag
+            $copiedHeaderFields = ' z=';
+            $first = true;
+            foreach ($copiedHeaders as $copiedHeader) {
+                if (!$first) {
+                    $copiedHeaderFields .= static::$LE . ' |';
                 }
+                //Fold long values
+                if (strlen($copiedHeader) > self::STD_LINE_LENGTH - 3) {
+                    $copiedHeaderFields .= substr(
+                        chunk_split($copiedHeader, self::STD_LINE_LENGTH - 3, static::$LE . self::FWS),
+                        0,
+                        -strlen(static::$LE . self::FWS)
+                    );
+                } else {
+                    $copiedHeaderFields .= $copiedHeader;
+                }
+                $first = false;
             }
+            $copiedHeaderFields .= ';' . static::$LE;
         }
-        foreach ($foundExtraHeaders as $key => $value) {
-            $extraHeaderKeys .= ':' . $key;
-            $extraHeaderValues .= $value . "\r\n";
-            if ($this->DKIM_copyHeaderFields) {
-                $extraCopyHeaderFields .= ' |' . str_replace('|', '=7C', $this->DKIM_QP($value)) . ";\r\n";
-            }
-        }
-        if ($this->DKIM_copyHeaderFields) {
-            $from = str_replace('|', '=7C', $this->DKIM_QP($from_header));
-            $to = str_replace('|', '=7C', $this->DKIM_QP($to_header));
-            $date = str_replace('|', '=7C', $this->DKIM_QP($date_header));
-            $subject = str_replace('|', '=7C', $this->DKIM_QP($subject_header));
-            $copiedHeaderFields = " z=$from\r\n" .
-                                  " |$to\r\n" .
-                                  " |$date\r\n" .
-                                  " |$subject;\r\n" .
-                                  $extraCopyHeaderFields;
-        }
+        $headerKeys = ' h=' . implode(':', $headersToSignKeys) . ';' . static::$LE;
+        $headerValues = implode(static::$LE, $headersToSign);
         $body = $this->DKIM_BodyC($body);
-        $DKIMlen = strlen($body); // Length of body
         $DKIMb64 = base64_encode(pack('H*', hash('sha256', $body))); // Base64 of packed binary SHA-256 hash of body
-        if ('' == $this->DKIM_identity) {
-            $ident = '';
-        } else {
-            $ident = ' i=' . $this->DKIM_identity . ';';
+        $ident = '';
+        if ('' !== $this->DKIM_identity) {
+            $ident = ' i=' . $this->DKIM_identity . ';' . static::$LE;
         }
-        $dkimhdrs = 'DKIM-Signature: v=1; a=' .
-            $DKIMsignatureType . '; q=' .
-            $DKIMquery . '; l=' .
-            $DKIMlen . '; s=' .
-            $this->DKIM_selector .
-            ";\r\n" .
-            ' t=' . $DKIMtime . '; c=' . $DKIMcanonicalization . ";\r\n" .
-            ' h=From:To:Date:Subject' . $extraHeaderKeys . ";\r\n" .
-            ' d=' . $this->DKIM_domain . ';' . $ident . "\r\n" .
+        //The DKIM-Signature header is included in the signature *except for* the value of the `b` tag
+        //which is appended after calculating the signature
+        //https://tools.ietf.org/html/rfc6376#section-3.5
+        $dkimSignatureHeader = 'DKIM-Signature: v=1;' .
+            ' d=' . $this->DKIM_domain . ';' .
+            ' s=' . $this->DKIM_selector . ';' . static::$LE .
+            ' a=' . $DKIMsignatureType . ';' .
+            ' q=' . $DKIMquery . ';' .
+            ' t=' . $DKIMtime . ';' .
+            ' c=' . $DKIMcanonicalization . ';' . static::$LE .
+            $headerKeys .
+            $ident .
             $copiedHeaderFields .
-            ' bh=' . $DKIMb64 . ";\r\n" .
+            ' bh=' . $DKIMb64 . ';' . static::$LE .
             ' b=';
-        $toSign = $this->DKIM_HeaderC(
-            $from_header . "\r\n" .
-            $to_header . "\r\n" .
-            $date_header . "\r\n" .
-            $subject_header . "\r\n" .
-            $extraHeaderValues .
-            $dkimhdrs
+        //Canonicalize the set of headers
+        $canonicalizedHeaders = $this->DKIM_HeaderC(
+            $headerValues . static::$LE . $dkimSignatureHeader
         );
-        $signed = $this->DKIM_Sign($toSign);
+        $signature = $this->DKIM_Sign($canonicalizedHeaders);
+        $signature = trim(chunk_split($signature, self::STD_LINE_LENGTH - 3, static::$LE . self::FWS));
 
-        return static::normalizeBreaks($dkimhdrs . $signed) . static::$LE;
+        return static::normalizeBreaks($dkimSignatureHeader . $signature);
     }
 
     /**
@@ -4596,7 +4796,7 @@ class PHPMailer
      */
     protected function doCallback($isSent, $to, $cc, $bcc, $subject, $body, $from, $extra)
     {
-        if (!empty($this->action_function) and is_callable($this->action_function)) {
+        if (!empty($this->action_function) && is_callable($this->action_function)) {
             call_user_func($this->action_function, $isSent, $to, $cc, $bcc, $subject, $body, $from, $extra);
         }
     }
@@ -4613,8 +4813,6 @@ class PHPMailer
 
     /**
      * Set an OAuth instance.
-     *
-     * @param OAuth $oauth
      */
     public function setOAuth(OAuth $oauth)
     {
diff --git a/core/core.php b/core/core.php
index 331d9709..e39a4d3f 100755
--- a/core/core.php
+++ b/core/core.php
@@ -36,7 +36,7 @@ class common {
 	const THUMBS_WIDTH = 640;
 
 	// Numéro de version 
-	const ZWII_VERSION = '10.0.083';
+	const ZWII_VERSION = '10.0.084';
 	const ZWII_UPDATE_CHANNEL = "v10";
 
 	public static $actions = [];