I haven't run a serious mail server for a while, but during the SMTP 
exchange, doesn't the receiving MTA host validate the IP address of the 
sender? And doesn't that show up in the envelope header? For example:

EHLO localhost.localdomain
250-mailhost.yourdomain.com Hello realname.spam.com [ 192.168.0.9 ], 
accepting invalid domain name


This could be one way to check, write a script that does a reverse IP lookup 
to see if the supplied name during the EHLO or HELO exchange matches the 
given name.

I'm also pretty sure that there is an m4 configuration setting in the 
sendmail.mc file that disallows all "invalid" domain names.

BAZ


BRYAN ZIMMER
----- Original Message ----- 
From: "David Phillips" <electrum at gmail.com>
To: "TCLUG Mailing List" <tclug-list at mn-linux.org>
Sent: Tuesday, September 14, 2004 8:21 PM
Subject: Re: [TCLUG] Verify senders email addy?


> On Tue, 14 Sep 2004 16:44:05 -0500, John T. Hoffoss
> <john.t.hoffoss at gmail.com> wrote:
>> VRFY is part of SMTP, but many disable this on their server
>
> I have NEVER seen an active server that supports VRFY.
>
> -- 
> David Phillips <david at acz.org>
> http://david.acz.org/
>
> _______________________________________________
> TCLUG Mailing List - Minneapolis/St. Paul, Minnesota
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> 



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