Re: IM2000 RNASP -- identifying message stores to recipients

Jonathan de Boyne Pollard <[email protected]> wrote:
> 
> The actual lookup mechanism is described in
> <URL:http://homepages.tesco.net./~J.deBoynePollard/Proposals/IM2000/Architecture/recipient-mua.html>
> in the section on locating message stores on Internet.  (I should 
> probably add some section anchors to that page.)

Okay, that's how I read the ASN.1, with the additional clarification of what
the presence of both means.  I think this sentence could be rethought:

  If both a domain name and a list of IP address and port pairs are supplied
  recipient MUAs must use the domain name.
  
This, to me, seems to be just begging for MUA authors to violate -- after all,
what's the point of allowing the address/port literals in the presence of the
domain name if not to provide a fallback for the client?  I think that if
domain literals are required (more below), they should be only allowed in the
absence of a domain name, to reduce confusion.

> There are two conflicting usage scenarios.  There's the "All _real_ message
> store owners will have the ability to create the relevant DNS resource record 
> sets." scenario on the one hand, and on the other hand there are the "I don't 
> want to be forced to own a domain name in order to run a message store.", the
> "My message store is entirely private to my small organisation, so I don't 
> need all of this extra mechanism.", and the "My DNS hosting service/DNS 
> software/network administrator won't let me set up 'SRV' resource records." 
> scenarios.
> 
> I strove to accommodate both camps, incorporating a reasonable bias towards
> the use of domain names whilst still permitting their avoidance if one 
> _really_ wanted it.

I understand this -- but it would seem to me that the domain literal case
makes it somewhat easier to abuse the protocol for UBM purposes while
providing little extra "real world" benefit.  I truly don't believe that
operating an outgoing message store oneself will be necessary for anyone who
does not operate their own content DNS service and cannot/will not find a sane
DNS host.

The ability to set up SRV records would then simply become one more way that
DNS hosting services could differentiate their service:  "We're
IM2000-friendly!  Lookit them simple web forms; a monkey could set up MSRAP
for your domain using them!".

Charles
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Charles Cazabon                           <[email protected]>
GPL'ed software available at:     http://www.qcc.ca/~charlesc/software/
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