>... I recently received an automated email from orbs.org ...
>They say I need to disable the external relay features of my server...

The cookbook is at <http://www.sendmail.org/antispam.html>. "Antispam
Provisions in Sendmail 8.8.8."

It's not hard to do, you just have to replace some lines in
/etc/sendmail.cf -- you should probably make a copy first just
in case you bodge something.

I presume that Sendmail 8.9 will be available as a package soon,
and the default in 8.9 is to turn off relaying. So it's a good
idea to upgrade.

	Larry