Set PHP to send mail through separate Exchange server

[ringobob]

I've got Ubuntu 7.10 installed as an internal web server with Apache 2 and PHP 5, and I've got a separate windows server that handles email through exchange. I know on Windows, I can just set the appropriate IP address in the PHP ini and it works. Is there some similar setting I can use here, or do I have to use something like postfix to interact with the Exchange server?

[ringobob]

I searched around some more and settled on using postfix, setting it to use a smarthost to handle all email needs and forwarded everything to the exchange server.

Everything checks out.