Caller ID and bounce messages (was: Microsoft submitting Caller ID as draft RFC)

["Harry Katz" <hkatz@xxxxxxxxxxxxxxxxxxxxxx>]

Splitting this out as a separate topic.

wayne [wayne@xxxxxxxxxxxxx] wrote (in part):

> -----Original Message-----
> From: owner-ietf-mxcomp@xxxxxxxxxxxx 
> [mailto:owner-ietf-mxcomp@xxxxxxxxxxxx] On Behalf Of wayne
> Sent: Sunday, April 11, 2004 6:35 AM
> To: IETF MXCOMP
> Subject: Re: Microsoft submitting Caller ID as draft RFC
> 
> > To be sure, the Caller ID mechanism could be used to 
> validate the 2821 
> > MAIL FROM. In fact we actually had the 2821 MAIL FROM as the first 
> > identity on our list, ahead of the 2822 headers, in early drafts of 
> > Caller ID.  In the end we dropped it because it either 
> added no useful 
> > information that was not already contained in the 2822 
> headers or led 
> > to incorrect or misleading conclusions from an end user 
> perspective.  
> > In other words, 2821 MAIL FROM adds nothing useful so why use it?
> 
> I am not convinced that the RFC2821 MAIL FROM adds nothing 
> useful.  In particular, I think it is very important for 
> email reliability to make sure a bounce gets generated to 
> email that has been rejected.
> Silently dropping email that doesn't pass certain tests is, 
> IMHO, a very big problem.

Rejecting a message at MAIL FROM or at end of DATA are equally effective
mechanisms for ensuring that bounce messages get generated.  RFC2821
MAIL FROM offers no advantage in that regard.  

Please note I'm not suggesting that performing checks on the RFC2821
MAIL FROM is entirely useless and should be stopped.  On the contrary,
there are a number of very useful things that can be done here such as
allow/deny lists, etc.  By all means let's continue doing those things
and if we can reject the message with a 4xx or 5xx code at that point,
great!

What I am saying is that for the purposes of this discussion under the
MARID charter, MAIL FROM doesn't add any information not already
available in the 2822 headers.  That's why we dropped it from Caller ID.

Thanks.

Harry