RE: Sendmail 8.11 configuration/security issue - some clarification

[<john65 () pobox com>]

<snip>
> The primary concern is with stopping mail with my domain as the sender and my
> domain as the recipient if the sender IP is not within networks which I
> control.
<snip>
> I'm not sure that this problem can be resolved within sendmail config files but
> if anyone knows differently, please let me know.
<snip>

Since this is a 'Basics' list, here are some places to get started.
There isn't a solution to your specific question, but you can learn this
stuff, and you might be able to work out an acceptable solution to
your problem.

In the sendmail source distribution
cf/README
cf/cf/knecht.mc
doc/op/op.ps

check_local package
http://www.digitalanswers.org/check_local/
This is a whole set of add-ons you can install, or you can just read it
to learn about rulesets.

I'd like to repeat the caution that I think this is a complex problem
and it will 'break' things. Remember that there are both ENVELOPE
addresses and HEADER addresses in email. Remember that your relay
will qualify unqualified HEADER sender addresses with the hostname of
your relay.