We have a Windows 2008R2 based domain with an Exchange 2007 mail system, the AD was migrated from a 2003 Enterprise system two years ago and we put in the new Exchange server at the same time migrating legacy mailboxes one at a time.
The MD had a PA and historically, whenever a Calendar invite was sent to the MD, her PA would get a copy of the invite. However, long
ago the PA left and her account was deleted from Exchange (and) Active Directory. We have used various tools including MCEDIT etc
to verify her demise :-) None the less, still whenever anyone invites the MD to a meeting they get a response back telling them that
the old PA's account cannot be found and so it frustrates users.
There is no rule in Outlook on the MD's mail/Outlook account as this has been set up on a new Cloud based system by ourselves
and so we are now quite stumped.