Validating incoming email addresses

Bob McClure Jr robertmcclure at
Mon Jun 27 17:43:29 UTC 2005

On Fri, Jun 24, 2005 at 10:50:43PM -0600, karlp at wrote:
> How do I go about blocking incoming email based on validating the sender's
> email address? I am getting spam email which is from a non-existent email
> address on my own domain. A look at the header shows it's not from my
> domain. I expected that. But, the From: field is from my domain
> (, even down to my server name (
> which NEVER sends email, per se, other than internally as in mail
> generated by cron jobs.
> Too much information, but I hope you get the gist of what I need.
> TIA,
> Karl

Depends on your email setup and where you want to stop the mail.  If
you want to stop it at the door, then it depends on what MTA
(sendmail, postfix, et al.) you are using.

If you want to punt it after your MTA accepts it but before delivery,
I strongly recommend SpamAssassin.  With or without SA, you can drop
it in the bit bucket with a well-crafted recipe in your ~/.procmailrc
(assuming procmail is your MDA (delivery agent)).  But with SA, and
assuming SA scores it as spam, then procmail can (1) divert the spam
to a bucket for inspection, (2) punt spam scoring over XX points, or
(3) summarily punt all identified spam (not recommended), or some

Let us know your constraints.  I'm well versed in Postfix and

Bob McClure, Jr.             Bobcat Open Systems, Inc.
robertmcclure at
God doesn't have (or need) a Plan B.

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