Speed up SMTP on Debian/Plesk servers
on Monday 7th April, 2008 Gabe speculated thusly…I recently found that sending emails via my server was painfully slow. After further invesitigation in to this issue I discovered that the server was performing reverse-DNS checks on client IPs. These were slow because they often didn’t work and had to wait for a timeout. The solution is to turn of reverse-DNS checking on the server by editing a config file as follows…
The modification must be made to the /etc/inetd.conf file:
smtp stream tcp nowait root /path/to/qmail/bin/tcp-env tcp-env -Rt0 ...
smtps stream tcp nowait root /path/to/qmail/bin/tcp-env tcp-env -Rt0 ...
It is necessary to restart inetd in order for the changes to take effect:
# kill -HUP `cat /var/run/inetd.pid`
Note, /etc/inetd.conf may be overwritten and the options you added will be removed if you make certain changes through Plesk CP, for example add MAPS server.
Posted in Debian, Linux, Operating System, Server