Force Messaging gateway to use higher perference mail server to send mail

Hi

I have a straight forward question.A company has changed their MX records but did not updated their DNS records and the Messaging Gateway tries to contact the lower perference server first (normaly) and that server is not responding.So i want to "tell" the server to use another server for the delivery,will this do the trick.

1.Add the destination domain in Protocols->Domains (deselect local domain)

2.On the delivery tab for that domain =>Optionally route this domain or email address - >   Destination hosts:(IP adress of the second mail server)

Will this force the Messaging Gateway always to deliver e-mail to that particular domain using the specified ip adress (Destination host) ?

Thanks