Hi there! You might be looking for the old Exchange Server Pro discussion forums. The forums existed from 2011 to 2013 before they were closed due to the overwhelming amount of spam I was having to deal with on a daily basis. You can read more about that here.
The forums remained closed but accessible as a read-only archive until recently, when some web server performance problems forced me to remove the forums software completely.
If you were looking for an answer to a problem that you're experiencing I apologise that the forums are no longer available for you to access. However, I can recommend that you post your problem in one of the other places that the Exchange community helps each other out.