Exchange Distribution sending message to user not in list

In Exchange 2007 we have a user mbx ( 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 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!
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Check that the users in the group don't also have forwarding setup, or perhaps rules to forward setup via Outlook

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If the email is a meeting request - then be aware of the Delegate settings. Many people add delegates and elect for the delegate to receive meeting-related emails.

Check list members for alternate recipients.
If list members were forwarding, it would show up on the email FROM field.
ichbinp3t3Author Commented:
In reviewing the header information sent over by the user, is in the From field.  I'm wondering if it was possible that someone had originally logged in as the user and created forwarding rules for the account.  In theory, w the current configuration being that the auto forward happens and the message is also delivered to's mailbox, would the message forward on to those users?
Yes - if the mailbox itself has a forward rule, and mail items are delivered to BOTH that mailbox and the DL (as an alternate recipient).

You can test this by dropping the alt-recipient and sending a quick test msg to the mailbox.
Delivery Rcpt turned on can be helpful.
ichbinp3t3Author Commented:
Accounts did have a rule setup, forwarding msg's to other users.  Thanks
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