Forged sender (Re: Router file naming convention)

["Alexey Lobanov" <aal@evidence-cpr.com>]

Hello Vince.

On 11 Jan 2003 at 9:52, Vince Puzzella wrote:

From:           	"Vince Puzzella" <vpuzzella@bluecatnetworks.com>
To:             	<zmailer@nic.funet.fi>
Subject:        	Re: Router file naming convention
Date sent:      	Sat, 11 Jan 2003 09:52:08 -0500

> Is there anyway to get the zmailer smtp server to test for forged sender
> addresses at the MAIL FROM:<> phase?
> Essentially, I want to perform a DNS MX record query to verify that  the
> source IP is a valid mail exchanger for the sender's domain.

Just note that you will reject a lot of legitimate mail. Outbound and inbound 
mail relays MAY differ by many reasons. I.e: load spreading at big public 
system; company affiliations using one domain, local outbound machines and 
single central inbound MX; etc, etc. You may wish to investigate this message 
properties as a real example.

The RFC2821 requirement "every mailsender must accept mail to @[ip.ad.dr.ess]" 
is something different.

Alexey

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