Qmail: nullenvsender patch
nullenvsender patch for qmail+starttls+smtp-auth
Charles Cazabon wrote this patch to modify qmail-smtpd to refuse messages from
the null envelope sender if they have more than one envelope recipient.
This is a trick to keep people from sending mass spam mails, emulating bounce
All we did was modify this patch so that it could be applied to a qmail
source tree that had already been patched for TLS and smtp-auth.