In case you want to send different e-mails through different connections, you can also pass the transport object directly to send() without a prior call to setDefaultTransport(). The passed object will override the default transport for the actual send() request.

$mail = new Zend_Mail();
// build message...
$tr1 = new Zend_Mail_Transport_Smtp('server@example.com');
$tr2 = new Zend_Mail_Transport_Smtp('other_server@example.com');
$mail->send($tr1);
$mail->send($tr2);
$mail->send();  // use default again

	Additional transports
	Additional transports can be written by implementing Zend_Mail_Transport_Interface.