Majordomo and gmail

I maintain a majordomo server for an organization that recently switched to
Google Apps for email.
With their old email provider they would send an email to one of the lists
and as the emails were sent out by the server they would get their own email
back.  They came to depend on this "Feature" as confirmation that everything
was working.

Gmail looks at an incoming message and determines (by message-id I think) if
this is a message that  originated within the destination account and drops
it if it did.  The result is that everybody thinks the server isn't working
when actually it is because they don't get a mail back.  I'm pretty sure
gmail is keying on the id because I can change other parameters of the
message (title, add footer, reply-to, etc) but the message still gets
dropped because the id is the same.

Has anyone dealt with this issue in the past?  After allot of thinking and
searching I haven't come up with a nice solution.  I think mailman and maybe
majordomo 2 both have an 'ack' feature, but I would hate to have to change
systems entirely just to get it.

Randall