send(Swift_Mime_Message $message, $failedRecipients = null) {@inheritdoc}

void __construct(LoggerInterface $logger) Create a new log transport instance

SparkPostTransport class SparkPostTransport extends

void registerPlugin(Swift_Events_EventListener $plugin) Register a plug-in

void __construct(ClientInterface $client, string $key, string $domain) Create

start() {@inheritdoc}

MailgunTransport class MailgunTransport extends

start() {@inheritdoc}

isStarted() {@inheritdoc}

stop() {@inheritdoc}