Qmail: mfcheck patch
mfcheck patch for qmail+starttls+smtp-auth
Nagy Balazs wrote the original patch to ensure that the domain name on the
evelope sender is a valid DNS name.
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.
To enable mfcheck:
echo 1 > /var/qmail/control/mfcheck