Auto forward problem

In myn organisation one of user has mailboxes in 2 different sites. A few months before the user moved to the other site and set Out of Office assistant to forward all his emails to the other mailbox. That worked fine during his vist but he noted after coming back that a copy of emails are still forwarded to the other mailbox although the OOA was turned off. Ther is no other on his Outlook 98 client. Ther is nothing unusual in the exchnage server.
Anybody aware of the problem.