I have had my Outlook 2007 open additional mailboxes via the advanced account settings. After updating to Office SP2, the list of emails in the additional account still displays, but I get a message for each mailbox item:
This item cannot be displayed in the Reading Pane.
Open the item to read its contents.
After double clicking the message, I get a small error box which displays just
Cannot open this item. Unknown Error.
Also, if I try to re-add the mailbox in the Advanced tab of my account settings, I get an error message
The name cannot be resolved. The connection to Microsoft Exchange is unavailable.
Outlook must be online or connected to complete this action.
However, the status bar indicates Online with Microsoft Exchange, and I can both send and receive emails from my primary account. What could be going wrong?
Best Answer
I've seen errors similar to this one, but it wasn't related to Outlook SP2. It was related to removing the last vestiges of the Exchange 2003 routing groups after we fully completed the migration to Exchange 2007. What was happening is that Outlook was storing the names of the mailboxes internally using an AD syntax to describe where to find the mailbox. Exchange 2007 uses a different location for that. This caused havoc in things like Delegates, replying to old emails, and the frequently-mailed-contacts list.
What was happening was that each user that was migrated from Exch2003 had an attribute called "LegacyExchangeDN" that pointed to the old AD location. Users created fresh in Exch2007 didn't have it, and didn't need it. After opening an SR with Microsoft to figure out what the heck, the fix was to add a new X500 address to each mailbox to the value of the old LegacyExchangeDN. This allowed cached Outlook entries (and there are a LOT of them) to find the mailbox.
That's a system-level fault, and it may not be your problem. But your symptoms seem close to what I've seen.