From: Jaycee on
I'm trying to understand something with the return-path in the message

Exchange 2003 mailboxes.
Messages sent out via Exchange 2007 hub transport servers.

Exchange 2003 mailboxes each have a contact in AD and their mailbox is
configured to forward to the contact email address.

When an individual email goes to the mailbox it forwards with no problem to
the contact address. I can also see their mailbox email address in the
return-path field of the header. It's not the original senders email

However, when an email is sent to the distribution group that the mailbox is
part of, the return-path of the message is <>, which means it's blank. Due
to this, our outbound mail filters have some issues handling this because of
the <> return-path field. They are delivered, but it just causes some extra
overhead and slows things down on the outbound mail filters.

Is this the way a distribution group message would work in this
case...leaving the return-path blank? Is there a way to ensure that the
return-path has an email address in it for the messages sent to the
distribution group?