Re: Operations requirement: no hop-by-hop

At 1:42 PM -0800 2/15/04, william(at)elan.net wrote:
>Point is that creating a barrier that will prevent unwanted traffic from
>coming through (which maybe a violation of the law or violation of the
>policies of the recepient) is not a bad thing to have as part of the
>mail tranmission sesssion.

We disagree here. Many people have said that they want to be able to 
have local multi-hop rules (for example, the edge MTA at my company 
might want to pass messages addressed to me to an internal MTA for my 
department, which then stores messages for me). From a design 
standpoint, then, what you want is transmission rules to have to be 
passed faithfully through all MTAs from one end to the other. I 
believe that doing so excessively complicates the transmission rules. 
Instead, there should be a separate policy plane for passing policy 
rules. MTAs on the way might want to follow those policies, but the 
policies are not part of the transmission plane.

>  > BTW, I'm not against having a way for a good sender to request
>  > permission from a recipient: in fact, that is a fine requirement. But
>>  that can be done in a different control plane than message
>>  transmission.
>Why? We may want to work on this on possibly slightly different protocol
>that defines it as authentication, but it does not mean it should not be
>possible for it to be used as part of email session.

"being possible for" is quite different than "being mandatory for at 
every step along the path".

--Paul Hoffman, Director
--Internet Mail Consortium