chiro-canto/public/contact/sendmail.php

<?php
// ini_set('display_errors', 1);
// ini_set('display_startup_errors', 1);
// error_reporting(E_ALL);

//Import PHPMailer classes into the global namespace
//These must be at the top of your script, not inside a function
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;

require './config.php';
//Load Composer's autoloader
require '../vendor/autoload.php';

//Instantiation and passing `true` enables exceptions
$mail = new PHPMailer(true);

$error_msg = "";
if (isset($_POST)) {
    if (isset($_POST['firstname'])) {
        $fname = $_POST['firstname'];
    } else {
        $error_msg .= "You have not entered a proper first name.\n";
    }
    if (isset($_POST['lastname'])) {
        $lname = $_POST['lastname'];
    } else {
        $error_msg .= "You have not entered a proper last name.\n";
    }
    if (isset($_POST['email'])) {
        $email = $_POST['email'];
    } else {
        $error_msg .= "You have not entered a proper email address.\n";
    }
    if (isset($_POST['subject'])) {
        $subject = $_POST['subject'];
    } else {
        $error_msg .= "You have not entered a proper subject.\n";
    }
    if (isset($_POST['message'])) {
        $message = $_POST['message'];
    } else {
        $error_msg .= "You have not entered a proper message.\n";
    }
}

echo $error_msg;

try {
    //Server settings
    // $mail->SMTPDebug = SMTP::DEBUG_SERVER;                      //Enable verbose debug output
    $mail->isSMTP();                                             //Send using SMTP
    $mail->Timeout = 60;
    $mail->SMTPKeepAlive = true;
    $mail->Host = $smtp_host;                     //Set the SMTP server to send through
    $mail->SMTPAuth = true;                                   //Enable SMTP authentication
    $mail->Username = $smtp_email;                     //SMTP username
    $mail->Password = $smtp_password;                               //SMTP password
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;         //Enable TLS encryption; `PHPMailer::ENCRYPTION_SMTPS` encouraged
    $mail->Port = 587;                                  //TCP port to connect to, use 465 for `PHPMailer::ENCRYPTION_SMTPS` above
    $mail->CharSet = "UTF-8";
    $mail->Encoding = 'base64';
    //Recipients
    $mail->addReplyTo($email, 'Message Sender');
    $mail->addAddress($admin_email, $admin_username);     //Add a recipient
    $mail->setFrom($email, 'Mailer');
    // $mail->addAddress('ellen@example.com');               //Name is optional
    // $mail->addCC('cc@example.com');
    // $mail->addBCC('bcc@example.com');

    //Attachments
    //$mail->addAttachment('/var/tmp/file.tar.gz');         //Add attachments
    //$mail->addAttachment('/tmp/image.jpg', 'new.jpg');    //Optional name

    //Content
    //$mail->isHTML(true);                                  //Set email format to HTML
    $mail->Subject = $subject;
    $mail->Body = $message;
    $mail->Body .= "\nSended by $fname $lname <$email>\n";
    // $mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

    $mail->send();
    $mail->smtpClose();
    echo 'Message has been sent';
} catch (Exception $e) {
    echo "Message could not be sent. Mailer Error: {$mail->ErrorInfo}";
}