meeting requests to certain user generate NDR of old email address

Anytime someone copies a specific user (we'll call her UserA) as an invite to a meeting in Outlook - the meeting organizer recieves an NDR from the System Administrator.  Somehow it is trying to copy an old user on all meeting requests sent to UserA.  The old user is not setup as a delegate nor do they have permission to access the inbox, calendar, or any other items of UserA to my knowledge.  The old user does not even exist in Active Directory or Exchange anymore - see details of NDR below.   UserA still recieves the meeting request - but it is unecessarily copying the old user on all meeting request creating a very annoying chain reaction of NDRs to other meeting organizers.  

The following recipient(s) cannot be reached:

      "Old User" on 11/5/2008 2:26 PM
            The e-mail account does not exist at the organization this message was sent to.  Check the e-mail address, or contact the recipient directly to find out the correct address.
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I have the same problem but have tried all kinds of way to try and resolve this but no luck. I will be interested in the outcome of this one.
The mystery user used to be a delegate of UserA, but when they were deleted, it doesn't automatically remove the delegate entry in UserA's mailbox.

Delegate functionality is achieved by 'hidden' mailbox rules being added by the system.  If the hidden system folder in the mailbox that stored the Inbox rules (the Associated Messages folder) becomes corrupted in some way - more common that you'd think - then the ability to 'see' the rules in the Delegates tab of Outlook disappears - but the rule still fires anyway.

You should be able to remove the corrupt rules using this procedure:  Be careful, you can badly mess up a mailbox unless you follow the instructions carefully.

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KevinITadminAuthor Commented:
Right on!  This fixed it.  Thanks a ton.
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