src/Message.php
public function send()
    {
        $eventManager = $this->getManager()->getEventsManager();
        if ($eventManager) {
            $result = $eventManager->fire('mailer:beforeSend', $this);
        } else {
            $result = true;
        }

        if ($result === false) {
            return false;
        }

        $this->failedRecipients = [];

        //send to queue
        $queue = $this->getManager()->getQueue();
        //$queueName = $this->

        if ($this->auth) {
            $queue->putInTube($this->queueName, [
                'message' => $this->getMessage(),
                'auth' => $this->smtp,
            ]);
        } else {
            $queue->putInTube($this->queueName, $this->getMessage());
        }

        /* $count = $this->getManager()->getSwift()->send($this->getMessage(), $this->failedRecipients);
    if ($eventManager) {
    $eventManager->fire('mailer:afterSend', $this, [$count, $this->failedRecipients]);
    }
    return $count;*/
    }
public function send()
    {
        $eventManager = $this->getManager()->getEventsManager();
        if ($eventManager) {
            $result = $eventManager->fire('mailer:beforeSend', $this);
        } else {
            $result = true;
        }

        if ($result === false) {
            return false;
        }

        $this->failedRecipients = [];

        //send to queue
        $queue = $this->getManager()->getQueue();
        //$queueName = $this->

        if ($this->auth) {
            $queue->putInTube($this->queueName, [
                'message' => $this->getMessage(),
                'auth' => $this->smtp,
            ]);
        } else {
            $queue->putInTube($this->queueName, $this->getMessage());
        }

        /* $count = $this->getManager()->getSwift()->send($this->getMessage(), $this->failedRecipients);
    if ($eventManager) {
    $eventManager->fire('mailer:afterSend', $this, [$count, $this->failedRecipients]);
    }
    return $count;*/
    }
Send the given Message like it would be sent in a mail client.

All recipients (with the exception of Bcc) will be able to see the other
recipients this message was sent to.

Recipient/sender data will be retrieved from the Message object.

The return value is the number of recipients who were accepted for
delivery.

Events:
- mailer:beforeSend
- mailer:afterSend

@return int

@see \Swift_Mailer::send()