Disable Reverse Lookups In QMail

Open /etc/xinetd.d/smtp_psa with your favourite text editor (vi, nano etc)

Find the line that starts with server_args and add “-Rt0” after the equals sign like so:

BEFORE:

server_args = /usr/sbin/rblsmtpd -r sbl-xbl.spamhaus.org /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true

AFTER:

server_args = -Rt0 /usr/sbin/rblsmtpd -r sbl-xbl.spamhaus.org /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true

Then save the file and issue:

service xinetd restart; service qmail restart

as root to restart qmail and apply the changes.

Make sure nothing else is modified apart from this as qmail will start to break horribly.

Cheers.