Use Magento (Zend_Mail) with Mailcatcher

Model_Observer.php

<?php

class Test_Test_Model_Observer {
    public function _construct() {}

    public function fixEmailConfig($observer) {

        if (Mage::getStoreConfigFlag('dev/email/enabled')) {
            $ip = $_SERVER["REMOTE_ADDR"];
            $config = array('port' => '1025');
            $tr = new Zend_Mail_Transport_Smtp($ip, $config);
            Zend_Mail::setDefaultTransport($tr);
        }
    }   
}