Duplicate mailing list replies due to Reply-To headers

Hi,

The forwarding of mailing list emails from @common-lisp.net to
@lists.common-lisp.net has caused a problem with duplicate emails on the
lists.  The reason is that the Reply-To header in outgoing emails contains the
@lists.common-lisp.net address, but the To header still contains the
@common-lisp.net address that the sender used, e.g.

Message-ID: 
 <CAN7nBXdm2w5xL-ZPFpwevaBKDN+weTa03GEFZKuHEyZOOgDt5g@mail.gmail.com>
To: Common Lisp Professionals <[email protected]>
Reply-To: Discussion list for Common Lisp professionals
 <[email protected]>

Unfortunately, some (many?) email clients will construct a reply containing
both the To and the Reply-To headers, so that will send the reply to both
addresses, e.g.

Message-Id: <[email protected]>
CC: Discussion list for Common Lisp professionals <[email protected]>,
        "[email protected]" <[email protected]>

and then everyone gets two copies.

-- 
Martin Simmons
LispWorks Ltd
http://www.lispworks.com/