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    <h3>Editing: SendmailTransport.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Mailer\Transport;

use Psr\EventDispatcher\EventDispatcherInterface;
use Psr\Log\LoggerInterface;
use Symfony\Component\Mailer\Envelope;
use Symfony\Component\Mailer\SentMessage;
use Symfony\Component\Mailer\Transport\Smtp\SmtpTransport;
use Symfony\Component\Mailer\Transport\Smtp\Stream\AbstractStream;
use Symfony\Component\Mailer\Transport\Smtp\Stream\ProcessStream;
use Symfony\Component\Mime\RawMessage;

/**
 * SendmailTransport for sending mail through a Sendmail/Postfix (etc..) binary.
 *
 * Transport can be instantiated through SendmailTransportFactory or NativeTransportFactory:
 *
 * - SendmailTransportFactory to use most common sendmail path and recommended options
 * - NativeTransportFactory when configuration is set via php.ini
 *
 * @author Fabien Potencier &lt;fabien@symfony.com&gt;
 * @author Chris Corbyn
 */
class SendmailTransport extends AbstractTransport
{
    private string $command = '/usr/sbin/sendmail -bs';
    private ProcessStream $stream;
    private ?SmtpTransport $transport = null;

    /**
     * Constructor.
     *
     * Supported modes are -bs and -t, with any additional flags desired.
     *
     * The recommended mode is &quot;-bs&quot; since it is interactive and failure notifications are hence possible.
     * Note that the -t mode does not support error reporting and does not support Bcc properly (the Bcc headers are not removed).
     *
     * If using -t mode, you are strongly advised to include -oi or -i in the flags (like /usr/sbin/sendmail -oi -t)
     *
     * -f&lt;sender&gt; flag will be appended automatically if one is not present.
     */
    public function __construct(string $command = null, EventDispatcherInterface $dispatcher = null, LoggerInterface $logger = null)
    {
        parent::__construct($dispatcher, $logger);

        if (null !== $command) {
            if (!str_contains($command, ' -bs') &amp;&amp; !str_contains($command, ' -t')) {
                throw new \InvalidArgumentException(sprintf('Unsupported sendmail command flags &quot;%s&quot;; must be one of &quot;-bs&quot; or &quot;-t&quot; but can include additional flags.', $command));
            }

            $this-&gt;command = $command;
        }

        $this-&gt;stream = new ProcessStream();
        if (str_contains($this-&gt;command, ' -bs')) {
            $this-&gt;stream-&gt;setCommand($this-&gt;command);
            $this-&gt;transport = new SmtpTransport($this-&gt;stream, $dispatcher, $logger);
        }
    }

    public function send(RawMessage $message, Envelope $envelope = null): ?SentMessage
    {
        if ($this-&gt;transport) {
            return $this-&gt;transport-&gt;send($message, $envelope);
        }

        return parent::send($message, $envelope);
    }

    public function __toString(): string
    {
        if ($this-&gt;transport) {
            return (string) $this-&gt;transport;
        }

        return 'smtp://sendmail';
    }

    protected function doSend(SentMessage $message): void
    {
        $this-&gt;getLogger()-&gt;debug(sprintf('Email transport &quot;%s&quot; starting', __CLASS__));

        $command = $this-&gt;command;

        if ($recipients = $message-&gt;getEnvelope()-&gt;getRecipients()) {
            $command = str_replace(' -t', '', $command);
        }

        if (!str_contains($command, ' -f')) {
            $command .= ' -f'.escapeshellarg($message-&gt;getEnvelope()-&gt;getSender()-&gt;getEncodedAddress());
        }

        $chunks = AbstractStream::replace(&quot;\r\n&quot;, &quot;\n&quot;, $message-&gt;toIterable());

        if (!str_contains($command, ' -i') &amp;&amp; !str_contains($command, ' -oi')) {
            $chunks = AbstractStream::replace(&quot;\n.&quot;, &quot;\n..&quot;, $chunks);
        }

        foreach ($recipients as $recipient) {
            $command .= ' '.escapeshellarg($recipient-&gt;getEncodedAddress());
        }

        $this-&gt;stream-&gt;setCommand($command);
        $this-&gt;stream-&gt;initialize();
        foreach ($chunks as $chunk) {
            $this-&gt;stream-&gt;write($chunk);
        }
        $this-&gt;stream-&gt;flush();
        $this-&gt;stream-&gt;terminate();

        $this-&gt;getLogger()-&gt;debug(sprintf('Email transport &quot;%s&quot; stopped', __CLASS__));
    }
}
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