IETF SMTP Working Group Proposal at smtpng.org

Mon Aug 26 14:26:58 UTC 2002

Brad Knowles <brad.knowles at skynet.be> writes:

> At 11:40 AM +0100 2002/08/23, Martin Cooper wrote:
> 
> >  How does it break mailing-lists? If the list sets the envelope sender
> >  to <list-request at listserv.domain.com> creating a MAIL-FROM shouldn't
> >  be a problem.
> 
> 	You may be surprised to discover this, but most mailing lists are 
> not proper mailing lists and are not managed with proper mailing list 
> management software.  Most mailing lists are actually handled as 
> aliases, and therefore do not modify the envelope sender address.
> 
> >                The only problem I can see is what to do about bounces
> >  (i.e. with a null envelope sender) - guess you could use header From
> >  instead maybe.
> 
> 	Actually, this is one area that the paper addresses.

       repudiated(mailfrom, ipsource) = {
            (lhs, rhs) = parse_addr(mailfrom);
            // handle "MAIL FROM:<>" somehow
            mxset = get_mx("MAIL-FROM" "." rhs);
            if (mxset == NULL)
                 return nonrepudiated;
                 ^^^^^^^^^^^^^^^^^^^^

OK - but unconditionally permitting null-return paths means that
spammers can drive a coach and horses through the hole it leaves. :-(

Martin