code: public function send($subject,$mock=false,$log='verbose') {
  		foreach ($this->recipients as $key => $rcpts) {
  			$mails = array();
  			foreach ($rcpts as $mail=>$title)
  				$mails[] = $this->buildMail($mail,$title);
  			$this->set($key,implode(', ',$mails));
  		}
  		$this->smtp->set('Subject', $this->encodeHeader($this->encode($subject)));
  		$body = '';
  		$hash=uniqid(NULL,TRUE);
  		$multipart = count($this->message) > 1;
  		if ($multipart)
  			$this->smtp->set('Content-Type', 'multipart/alternative; boundary="'.$hash.'"');
  		$i=0;
  		foreach ($this->message as $msg) {
  			if ($multipart) {
  				$body .= '--'.$hash.static::$EOL;
  				$body .= 'Content-Type: '.$msg['type'].static::$EOL.static::$EOL;
  			} else
  				$this->smtp->set('Content-Type', $msg['type']);
  			$body .= $msg['content'].static::$EOL.static::$EOL;
  		}
  		if ($multipart)
  			$body .= '--'.$hash.'--'.static::$EOL;
  		$success = $this->smtp->send($this->encode($body),$log,$mock);
  		$f3 = \Base::instance();
  		if (!$success && $f3->exists('mailer.on.failure',$fail_handler))
  			$f3->call($fail_handler,array($this,$this->smtp->log()));
  		return $success;
  	}
docs: send message
  @param $subject
  @param bool $mock
  @param bool|string $log log level [false,true,'verbose']
  @return bool