We hear there’s a subtle bug that can cause strange effects when upgrading a mailbox store to Exchange 2007. It seems to be connected with the use of BlackBerry Enterprise Server (BES).

Here at Tech-Ed, we heard from two IT professionals that some of their Exchange users’ mailboxes became “invisible” after a migration to Exchange 2007. This appeared to be connected with the use of BES — the only users affected were those who used BlackBerrys.

The fix was to remove a rogue PR_HIDDEN property from the affected user’s mailbox.

It’s thought you can prevent this from happening by ensuring you upgrade the BES server first, including the Collaboration Data Objects (CDO) component.

… Richi Jennings, with thanks to Sekou Page