We have BES 5.0 set up in Exchange 2010. All the tests show the server is able to communicate, however none of the blackberry phones will activate. All of these phone worked in the past when the users were running with Notes.
In enterprise activation, I put in the email address and activation password and then choose activate and then nothing happens. No percentage or anything. I tried shutting the phone down and pulling the battery for two minutes, but that didn't help either.
One thing I thought could be the problem is that the email to the domain is received externally, scanned for spam and then delivered to the Exchange server. So mail.domain.com resolves to another location and not the Exchange server.
I also read on a website where deleting and undeleting the servicebook called desktop synch will help the problem. I tried that on one phone and now it has overridden the enterprise activation and is stuck at 68% trying to resynch the service book.
I do have port 3101 set up to forward to the BES server. Not sure if there is anything else required.