I have a problem with a Exchange 2007 Server environment that may or may not be very simple to solve. Every once in a while, if an existing calendar entry is opened, and then a reminder invitee email is sent from a users' Outlook client, that user will get a bounce back of about 10-15 former employees saying that Exchange 2007 could not find their addresses. Those people were never added to the outgoing reminder email, they just show up. Some are several years old. We migrated to Exchange 2007 from 2003 about 5-6 months ago.
The most recent time this happened, a few random people received the message that were current users but were not addressed.
Could this be related to delegates? We had delegate issues before, but I thought all was cleaned up.