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RE: blowback, was A new SMTP "3821" [Re: FTC stuff...........]

2005-01-10 12:44:29

On Sun, 9 Jan 2005 terry(_at_)ashtonwoodshomes(_dot_)com wrote:


Agreed, but near sighted.  If the sending MTA had done some sort of 
validation to ensure the message
was not forged when it accepted it, then we wouldn't have a blowback problem. 
 You cannot blame
subsequent MTA's in the path for detecting and rejecting bad email when its 
something the first hop
MTA could (and should) have done in the first place!

And just what sort of validation would that be?

You are talking about a normal closed relay. It cannot use SPF to validate 
its own users.

His point I think is that if the virus is trying to send directly to the MTA 
it would get rejected
with no bounce back (because the virus wouldn't process a bounce).

If an MTA.1 accepted a virus message, and tried relaying it to MTA.2, when 
MTA.2 rejects it as
forged, and MTA.1 processes a bounce, well, NO SYMPATHY FOR MTA.1, it should 
have taken steps to
prevent the virus/forgery etc from being accepted by itself in the FIRST 
PLACE.

Your lack of sympathy for MTA.1 is unfortunate, but unrealistic.  Even
taking steps to prevent viruses does not catch all virues.  Even using
SMTP AUTH on a closed relay does not prevent forgery.

                --Dean


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