I have the strangest problem - I have set permissions in AD (Server 2000/2003 - Exchange 2000)for one of our users to have full rights to send e-mail as her immediate supervisor. This was working fine until about 2 weeks ago, all of the sudden she started getting NDR's that she doesn't have permission to send to any recipient when sending e-mail as her supervisor. I went into AD and looked at the supervisor's security tab, and the user was gone - disappeared completely from the ACL list. So I readded her, which solved the sending problem, and about 20 minutes later, it happened again, and she had disappeared from the ACL list again. I have been unable to find anything about this issue anywhere on the net - please help!