Symfony Mailer simple internal smpt transport

.env.local

MAILER_DSN=insmtp://0.0.0.0

di.php

<?php

declare(strict_types=1);

use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;

return static function (ContainerConfigurator $di): void {
    $di
        ->services()
        ->set(InternalSmtpTransportFactory::class)
        ->autowire()
        ->tag('mailer.transport_factory')
    ;
};

InternalSmtpTransportFactory.php

<?php

declare(strict_types=1);

use Symfony\Component\Mailer\Transport\AbstractTransportFactory;
use Symfony\Component\Mailer\Transport\Dsn;
use Symfony\Component\Mailer\Transport\Smtp\SmtpTransport;
use Symfony\Component\Mailer\Transport\Smtp\Stream\SocketStream;
use Symfony\Component\Mailer\Transport\TransportInterface;

final class InternalSmtpTransportFactory extends AbstractTransportFactory
{
    public function create(Dsn $dsn): TransportInterface
    {
        $stream = (new SocketStream())
            ->setHost($dsn->getHost())
            ->setPort($dsn->getPort() ?? 25)
            ->setStreamOptions([
                'ssl' => [
                    'verify_peer' => false,
                    'verify_peer_name' => false,
                ],
            ])
            ->disableTls()
        ;

        return new SmtpTransport($stream, null, $this->logger);
    }

    protected function getSupportedSchemes(): array
    {
        return ['insmtp'];
    }
}