== INSTRUCTIONS ==

composer require symfony/mailer

then backup smtp.php in inc/mailhandlers/

=== BEGIN PHP CODE ===

<?php
/**
 * MyBB 1.9
 * Copyright 2014 MyBB Group, All Rights Reserved
 * Copyright 2026 Setsuna Software L.C. and Kazuo Kuroi
 *
 * Website: http://www.mybb.com
 * License: http://www.mybb.com/about/license
 *
 * Symfony Mailer integration is licensed under the MIT License.
 * See: https://symfony.com/doc/current/mailer.html
 */

if(!defined("IN_MYBB"))
{
    die("Direct initialization of this file is not allowed.<br /><br />Please make sure IN_MYBB is defined.");
}

use Symfony\Component\Mailer\Mailer;
use Symfony\Component\Mailer\Transport\Smtp\EsmtpTransport;
use Symfony\Component\Mime\Email;
use Symfony\Component\Mime\Address;

if(!defined('MYBB_SSL'))
{
    define('MYBB_SSL', 1);
}

if(!defined('MYBB_TLS'))
{
    define('MYBB_TLS', 2);
}

class SmtpMail extends MailHandler
{
    /**
     * SMTP host.
     *
     * @var string
     */
    public $host = '';

    /**
     * SMTP port.
     *
     * @var int
     */
    public $port = 25;

    /**
     * SMTP username.
     *
     * @var string
     */
    public $username = '';

    /**
     * SMTP password.
     *
     * @var string
     */
    public $password = '';

    /**
     * Whether to use implicit SSL (port 465).
     *
     * @var bool
     */
    public $use_ssl = false;

    /**
     * Whether to use STARTTLS (port 587).
     *
     * @var bool
     */
    public $use_tls = false;

    /**
     * Connection timeout in seconds.
     *
     * @var int
     */
    public $timeout = 5;

    /**
     * The last error message.
     *
     * @var string
     */
    public $last_error = '';

    /**
     * Plain text message body, stored separately so Symfony can
     * build multipart messages natively rather than consuming
     * MailHandler's raw MIME string.
     *
     * @var string
     */
    public $message_text = '';

    function __construct()
    {
        global $mybb;

        if(empty($mybb->settings['smtp_host']))
        {
            $this->host = @ini_get('SMTP') ?: 'localhost';
        }
        else
        {
            $this->host = $mybb->settings['smtp_host'];
        }

        switch((int)$mybb->settings['secure_smtp'])
        {
            case MYBB_SSL:
                $this->use_ssl = true;
                $this->port    = 465;
                break;
            case MYBB_TLS:
                $this->use_tls = true;
                $this->port    = 587;
                break;
            default:
                $this->port = 25;
                break;
        }

        // Explicit port setting overrides the protocol default
        if(!empty($mybb->settings['smtp_port']))
        {
            $this->port = (int)$mybb->settings['smtp_port'];
        }
        elseif(empty($mybb->settings['smtp_port']) && @ini_get('smtp_port'))
        {
            $this->port = (int)@ini_get('smtp_port');
        }

        $this->username = $mybb->settings['smtp_user'] ?? '';
        $this->password = $mybb->settings['smtp_pass'] ?? '';
    }

    /**
     * Override MailHandler's raw MIME multipart construction.
     * Symfony Mailer handles multipart natively, so we store the
     * HTML and plain text parts separately and skip the raw boundary
     * building that MailHandler would otherwise do.
     *
     * @param string $message      HTML message body
     * @param string $message_text Plain text alternative
     */
    function set_html_headers($message, $message_text = '')
    {
        $this->message      = $message;
        $this->message_text = $message_text ?: strip_tags($message);
        // Intentionally do not call parent — we do not want the raw
        // MIME boundary construction; Symfony handles this for us.
    }

    /**
     * Build and return a configured EsmtpTransport instance.
     *
     * @return EsmtpTransport
     */
    protected function build_transport()
    {
        $transport = new EsmtpTransport(
            $this->host,
            $this->port,
            $this->use_ssl  // true = implicit SSL (port 465), false = plain or STARTTLS
        );

        if($this->use_tls)
        {
            $transport->getStream()->setStreamOptions([
                'ssl' => [
                    'verify_peer'       => true,
                    'verify_peer_name'  => true,
                    'allow_self_signed' => false,
                ],
            ]);
        }

        if(!empty($this->username))
        {
            $transport->setUsername($this->username);
        }

        if(!empty($this->password))
        {
            $transport->setPassword($this->password);
        }

        return $transport;
    }

    /**
     * Sends the email via Symfony Mailer.
     *
     * @return bool True on success, false on failure.
     */
    function send()
    {
        try
        {
            $transport = $this->build_transport();
            $mailer    = new Mailer($transport);
            $email     = new Email();

            // From — from_named is already formatted as "Name" <email> by MailHandler
            if(!empty($this->from_named) && $this->from_named !== $this->from)
            {
                $email->from(Address::create($this->from_named));
            }
            else
            {
                $email->from($this->from);
            }

            // Reply-To / Return-Path
            if(!empty($this->return_email))
            {
                $email->replyTo($this->return_email);
            }

            // To — MailHandler stores comma-separated addresses in $this->to
            $recipients = array_map('trim', explode(',', $this->to));
            foreach($recipients as $recipient)
            {
                if(!empty($recipient))
                {
                    $email->addTo($recipient);
                }
            }

            $email->subject($this->orig_subject ?: $this->subject);

            // Body — use parse_format set by MailHandler::build_message()
            if($this->parse_format === 'html' || $this->parse_format === 'both')
            {
                $email->html($this->message);
                if(!empty($this->message_text))
                {
                    $email->text($this->message_text);
                }
            }
            else
            {
                $email->text($this->message);
            }

            // Additional headers — skip anything Symfony sets itself
            if(!empty($this->headers))
            {
                $skip = [
                    'from',
                    'reply-to',
                    'return-path',
                    'message-id',
                    'content-type',
                    'content-transfer-encoding',
                    'mime-version',
                    'x-priority',
                    'x-mailer',
                ];

                $raw_headers = explode("\n", trim($this->headers));
                foreach($raw_headers as $header_line)
                {
                    $header_line = trim($header_line);
                    if(empty($header_line))
                    {
                        continue;
                    }

                    $parts = explode(':', $header_line, 2);
                    if(count($parts) !== 2)
                    {
                        continue;
                    }

                    $name  = trim($parts[0]);
                    $value = trim($parts[1]);

                    if(in_array(strtolower($name), $skip))
                    {
                        continue;
                    }

                    $email->getHeaders()->addTextHeader($name, $value);
                }
            }

            $mailer->send($email);
            return true;
        }
        catch(\Symfony\Component\Mailer\Exception\TransportExceptionInterface $e)
        {
            $this->set_error($e->getMessage());
            $this->fatal_error("Symfony Mailer transport error: " . $e->getMessage());
            return false;
        }
        catch(\Exception $e)
        {
            $this->set_error($e->getMessage());
            $this->fatal_error("Mailer error: " . $e->getMessage());
            return false;
        }
    }

    /**
     * Get the last error message.
     *
     * @return string
     */
    function get_error()
    {
        return $this->last_error ?: 'N/A';
    }

    /**
     * Set the last error message.
     *
     * @param string $error
     */
    function set_error($error)
    {
        $this->last_error = $error;
    }
}