[Asrg] where the message originated

[David Wilson]

On Tue, 2009-01-13 at 20:46 -0500, Rich Kulawiec wrote:
> On Tue, Jan 13, 2009 at 07:13:39PM -0600, Gordon Peterson wrote:
> > That's a bogus argument.  You're basically saying that "someone else  
> > will probably pick up on this" and using that as a (lame) excuse to lob  
> > a grenade their way.
> 
> Perhaps you should review the SMTP protocol: sending a 5XX response
> *refuses* delivery of a message.  It does not transmit (or retransmit)
> a message.  It is difficult to see how one can be accused of "lob[bing]
> a grenade" when one has never taken possession of it.

Because of the normal action of an MTA when it receives such an 5XX
response, i.e. it sends a non-delivery message, normally containing the
message, to the return path address. If that return path address is
forged, then the infection is bounced elsewhere. That is the grenade.