In Exchange 2007 we have a user mbx (UserMBX@domain.com) that is setup to autmatically forward messages to a DL using Delivery Options. The option to "Deliver message to both forwarding address and mailbox" is also checked.
The DL is configured as a Mail-Enabled Security Group and has 3 members, all Mail Contacts.
We are getting reports that messages being sent to UserMBX@domain.com are not only going to the DL list members, but also a user who is not part of the DL. I've tracked down a sample message and run message tracking against all mbx and ht servers in order to see the message flow through our environment, but have not been able to make sense of this.
Any help is appreciated!