On Fri, 13 Feb 1998, Terry Knab wrote:
> This is called relaying. It is caused by older sendmail configs
> that allow _anyone_ to connect and send mail from a server. We've
> configured our sendmail for this not to be an issue. :)
With a few notable exceptions, most experienced ISP's don't except
relays from unknown sources. Unfortunately, there are hundreds of new
systems going online around the world every month. Most of the spam I
receive personally has been relayed through overseas (non-USA)
systems. As P.T. Barium said, "There is a sucker born every minute."
In many cases, the first indication of a security problem is when the
unsuspecting mail system is flooded by relay spam to the point of
failure.
Relay spam on a large scale is are relatively new problem. The big
time spammers switched to relay when folks started filtering spam
domains and IP addresses on a large scale. One of the most famous
spammers had bought about one hundred domain names which were all
promptly filtered along with his two Class C address blocks. For
now, one of the few effective routes for massive spamming is to use a
third party relay. With luck, the relay hole will also be plugged
pretty soon. Most sysadmins take action quickly when someone steals
their resources and makes them look bad at the same time.
- murr -
Follow-Ups:
References:
|
|
