| | Re: Upgraded from Exch2003 to Exch 2010... now only 1/2 our BB's work!?!
We just had this exact issue happen to us this past weekend. Throttling is causing your issue. You will need to contact me for the website since this is my first post and I am not permitted to do so yet.
Your issues are 1: Did you add additional stores and move users into them? You have to run a script after the addition of each new store.
2: Throttling. There is a powershell command to run that fixes this issue of only part of users connecting to the BES server.
3. Restarting your Exchange server first and then your BES server and you should be back in business.
We went from having only 14 users at a time working to all 30.