Author: Ted Cooper Date: To: exim-users Subject: Re: [exim] A cry for help - are there any plusnet admins out there ?
On 25/03/11 00:50, Dave Restall - System Administrator,,, wrote: > What are the current RFC's regarding
> good mail server etiquette ?
Don't do sender callouts. It's abusive and causes more problems than it
solves.
I was the lucky recipient of several DDoS as a result of Joe Jobs at
some very small, low traffic mail servers. Receiving millions of
connections for sender callouts and countless bounce messages, ALL of
which went to valid email accounts made the poor little servers melt.
Since every callout was accepted, they helped no one and prevented no spam.
All the domains in question had strict SPF records which would have been
a much cheaper way to reject all those spoofed emails.
I've also had my servers blacklisted for rejecting sender callouts with
a blacklist of bad actors. ips.backscatter.org - Almost every server
that does sender callouts is on this list.
There are also numerous other, "cheaper" ways to filter spam that that
focus the work on your resources and do not impact on innocent 3rd party
servers.
