EHLO; MAIL FROM: Aaron; RCPT TO: You; SUBJECT: Enjoy!
This topic is rarely addresssed because most Outlook/Exchange users tend to be domain joined, but in my testing I ran into a few issues that are worth making a public note of. First off, I want to say that I only tested this scenario with Exchange 2007, but this may be relevant to Exchange 2003 as well.
I did not run into any issues when using Exchange 2007 with Outlook when the Exchange server was also the Domain Controller (DC) and Global Catalog (GC) server. When I separated the Exchange 2007 server and the DC/GC I ran into an issue with Outlook not authenticating properly to the Directory Service through the RPC over HTTPS proxy. I was not able to track down the full reason behind the problem, but I figured out the solution as well as contributing factors.