Qmail-smtpd will reject every recipient address for a message if  the envelope sender address is listed in badmailfrom. A line in badmailfrom may be of the form @host, meaning every address at host To install: cd /src/qmail-1.03 fetch http://tomclegg.net/software/patch-qmail -badmailfrom-wildcard patch < qmail-badmailfrom-wildcard.patch make qmail-smtpd install -m 755 qmail-smtpd /var/qmail/bin/qmail-smtpd To refuse mail from any sender which ends [...]