I had the need to send outgoing email using our hosted MS Exchange server. I configured Postfix on Debian for this task. I had to do some troubleshooting to get it to work correctly, so I wrote up a concise procedure. I hope someone else finds it useful.

fritzmahnke.com/2010/12/25/use-postfix-to-send-email-through-microsoft-exchange-server

(I hope it's okay to post a URL this way)

-Fritz