Is some mobiles, i was getting "Unfortunately, Exchange Services has stopped" error message constantly and this problem couldn't be solved even eith re-installed ROM. If you have the same problem, check the following solution.
The problem usually appears when email app trying to receive data, but many other apps are triggering this error. To solve this problem, go to "Manage Apps > All > Email" and click on "Clear Data". This worked for me and this message stopped.