src/Viserio/Component/Mail/Provider/MailServiceProvider.php
public function getFactories(): array
    {
        return [
            TransportFactory::class    => [self::class, 'createTransportFactory'],
            MailManager::class         => [self::class, 'createMailManager'],
            MailerContract::class      => [self::class, 'createMailer'],
            QueueMailerContract::class => static function (ContainerInterface $container) {
                return $container->get(MailerContract::class);
            },
            'mailer'                   => static function (ContainerInterface $container) {
                return $container->get(MailerContract::class);
            },
        ];
    }
public function getFactories(): array
    {
        return [
            TransportFactory::class    => [self::class, 'createTransportFactory'],
            MailManager::class         => [self::class, 'createMailManager'],
            MailerContract::class      => [self::class, 'createMailer'],
            QueueMailerContract::class => static function (ContainerInterface $container) {
                return $container->get(MailerContract::class);
            },
            'mailer'                   => static function (ContainerInterface $container) {
                return $container->get(MailerContract::class);
            },
        ];
    }
{@inheritdoc}