It seems to be a morning of odd little problems and this is no exception. A number of users have been reporting the following error when sending/receiving email from within Outlook.

0×8004010F An object could not be found

The curious thing is that emails seemed to be sending and receiving ok but the message was reported afterwards.

The users local configuration seems ok and the fact that a number of users have reported it implies that the problem must be on the Exchange Server. Searching for the problem it seems to be related to the Offline Address List synchronisation.

Right clicking Properties in the Database Management tab (under Server Config->Mailbox) in the Exchange Management Console and reapplying the client settings offline address book seemed to do the trick. A related Microsoft article is here.