Neil, 

according to Stalker's docs:

============================================================================

To protect your site from spammers, the SMTP module can verify the
Return-Path address (specified with the Mail From SMTP command) of incoming
messages.

When the Verify Return-Path option is selected in the SMTP Service Settings,
the SMTP module parses the message Return-Path (Mail From) addresses, and
the module refuses to receive a message if:

*    the Return-Path domain name is an empty string (no domain specified);
*    the Return-Path address is routed (via the Server Router) to the ERROR
address; 
*    the Domain Name System does not have neither MX nor A records for the
Return-Path domain (an unregistered domain);
*    the Domain Name System has an MX record for the Return-Path domain, but
it points to an A-record that does not exist (a faked domain);
*    the A-record or the the highest-priority MX record for the Return-Path
domain points onto an IP address included in the Black List;
*    the Return-Path domain name is specified as an IP address, and that
address is not included into the Client Hosts list.

============================================================================

I guess I don't know nearly enough about the mail server commands.

So the Mail From:, does it VERIFY the validity of the sender address?

Can you or someone else maybe give me the actual step-by-step rundown of an
SMTP connection, or at least point me to a reference for the steps a mail
server takes to perform this?

Thanks,

Chris

> From: Neil Herber <[EMAIL PROTECTED]>
> Reply-To: "SIMS Discussions" <[EMAIL PROTECTED]>
> Date: Mon, 10 Feb 2003 11:10:30 -0500
> To: "SIMS Discussions" <[EMAIL PROTECTED]>
> Subject: Re: Verifying return-paths
> 
> It is rumored that on or about 2003-02-10 9:55 AM -0600, Chris Wagner
> wrote as follows:
>> If I have SIMS setup to verify return paths, can I assume that the mailbox
>> SIMS says it's coming from is accurate and not spoofed in any way?
>> 
>> The reason I ask is this - at least ONE of these accounts hasn't been used
>> for a very long time, and is coming from a local provider, journey.com.
> 
> Chris
> 
> My understanding is that SIMS does a DNS lookup on the Return-Path
> domain and makes sure it returns a valid IP. It does not do any kind
> of client verify.
> 
> So if some one spoofs "[EMAIL PROTECTED]" SIMS will accept that
> as valid, whereas "[EMAIL PROTECTED]" would
> probably fail - unless someone goes and registers that domain.
> 
> The attachments and spoofed return paths suggest a KLEZ type virus.
> 
> -- 
> Neil
> 
> Neil Herber
> Corporate info at http://www.eton.ca/
> Eton Systems, 15 Pinepoint Drive, Nepean, ON, Canada K2H 6B1
> Tel: (613) 829-4668
> 
> 
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