code: public function save($filename) {
  		$f3 = \Base::instance();
  		$lines = explode("\n",$this->smtp->log());
  		$start = false;
  		$out = '';
  		for($i=0,$max=count($lines);$i<$max;$i++) {
  			if (!$start && preg_match('/^354.*?$/',$lines[$i],$matches)) {
  				$start=true;
  				continue;
  			} elseif (preg_match('/^250.*?$\s^QUIT/m',
  				$lines[$i].($i+1 < $max ? "\n".$lines[$i+1] : ''),$matches))
  				break;
  			if ($start)
  				$out.=$lines[$i]."\n";
  		}
  		if ($out) {
  			$path = $f3->get('mailer.storage_path');
  			if (!is_dir($path))
  				mkdir($path,0777,true);
  			$f3->write($path.$filename,$out);
  		}
  	}
docs: save the send mail to disk
  @param $filename