Implement Access Control List With MailScanner???

[Walt Wyndroski]

Hello all,
    I've been doing some serious googling over the 2-3 days about how to
implement a type of ACL (access control list) for Sendmail which would help
in preventing the spoofing of my domain to my users. The only thing I can
find are rulesets which are inserted direclty into the sendmail.cf, which is
something that I really want to avoid. I was hoping MailScanner would allow
me to do this. Here is my setup:

 Kernel Version    2.4.22-1.2194.nptlsmp
SendMail RPM Version    sendmail-8.12.10-1.1.1
Procmail RPM Version    procmail-3.22-11
MailScanner RPM Version    mailscanner-4.30.2-1

If an email arrives at my mail server with the from header as user at mydomain,
I need to further look at the message to see if the message originated from
one of the subnets for which I relay. If it did, I'll accept it. If it
didn't, I'll discard it. If anyone knows of a Sendmail m4 rule for this,
please point me in the right direction and accept my apologies for being on
the wrong list. :) Otherwise, if MailScanner can already do this or if
someone has already written a custom function for this, please point me in
the right direction.

Walt Wyndroski

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