doMailFromCommand example

        if (microtime(true) - $this->lastMessageTime > $this->pingThreshold) {
            $this->ping();
        }

        if (!$this->started) {
            $this->start();
        }

        try {
            $envelope = $message->getEnvelope();
            $this->doMailFromCommand($envelope->getSender()->getEncodedAddress());
            foreach ($envelope->getRecipients() as $recipient) {
                $this->doRcptToCommand($recipient->getEncodedAddress());
            }

            $this->executeCommand("DATA\r\n", [354]);
            try {
                foreach (AbstractStream::replace("\r\n.", "\r\n..", $message->toIterable()) as $chunk) {
                    $this->stream->write($chunk, false);
                }
                $this->stream->flush();
            } catch (TransportExceptionInterface $e) {