I posted on this before and thought I had it licked. Very intermittently outlook prompts for your username and password, over and over again, you can enter it as many times as you like but it is never happy. If you click cancel and then click on "need pasword" in the lower right it will be happy. We just re-did everything and are running Exchange 2007 on Server 2008. Also I used the "trick" for a single cert for all of the Exchange functions, and my external machine name is different then my internal name, so exchange.xxxx.com and exchange.xxxxxx.local. Please help.