A pretty important Entourage 2004 fix was RTW’d last night.
KB article: http://support.microsoft.com/kb/948056
Look in there and you’ll see:
_Stability is improved for users of Exchange Server accounts.
This update fixes an issue that could cause loss of e-mail messages, calendar events, or contacts, for users of accounts on a server that is running Exchange Server._
You will want to download this pretty quick and get it into your QA process. It’s version 11.4.0. This will fix a data loss issue when using Entourage 2004 against an Exchange server.
The bug occurs due to a bad logic assumption. Entourage 2004 treats its local database as authoritative to the mail stored in your mailbox. As such, if the Exchange server happens to be virus-scanning your mailbox when you synchronize your mail, Exchange will refuse to allow Entourage access to the items being scanned. Since Entourage receives no information on the existence of those items, it will mark them for deletion in its local database.
On the next sync, you lose all of those items in the mailbox too. In cases we noted, users were losing large swaths of email at once (on the order of 2-3 weeks’ worth all at once).
If you have a deleted-item retention policy on Exchange, it’s not that bad. You can actually retrieve the mail by going to Outlook Web Access and going to Options/Recover Deleted Items. You can also do this in Outlook 2003 or 2007 against the same mailbox.
If you do not realize the mail is missing and it goes past your deleted item retention period, you get to hit the backup tapes.
This bug was a really, really hard one to track down and eradicate, but I’m much more comforted in knowing the public will soon have the fruits of the debugging labor.
Incidentally, Entourage 2008 (Office 2008) contains this fix and you should not experience the same issue on the newest Office release.