Entourage 2008 stops receiving Exchange email
Entourage 2008 stops receiving email from an Exchange account. The user continues to get Sent mail but there is no new mail in the Inbox and no error messages. Outlook Web Access still works properly. If this happens:
-Verify that Entourage is online. On the Entourage menu, make sure that Work Offline is not checked.
-Entourage copies items from a Microsoft Exchange account and stores them in the Entourage cache; if this cache becomes corrupted, it may cause synchronization problems with the Exchange server.
Solution: Empty the Inbox cache- by right click on the Inbox folder and select Folder Properties. Click Empty under Empty Cache. Entourage will re-download the Inbox contents and Entourage will begin receiving email again.
From http://forums.macrumors.com/archive/index.php/t-731364.html and