Re: IM2000 RNASP -- identifying message stores to recipients

JdeBP> If both a domain name and a list of IP address and port 
JdeBP> pairs are supplied recipient MUAs must use the domain name.

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

We could turn [ServiceLocation] from a SEQUENCE into a CHOICE.  I've only
reflected upon it for a couple of minutes, but it doesn't seem to have any
widespread consequences.

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

On the one hand:  Eliminating the ability to use literal IP address and port
number pairs in notifications, in favour of always using domain names, would
simplify things and would be more in accord with other parts of the system. 
It would make the discussion of MSRAP service mobility significantly simpler,
bringing it into line with the discussion of RNASP service mobility.  It would
parallel the elimination of recipient mailbox names that contain literal IP
addresses.

On the other hand:  What you say above does partially attempt to have things
both ways.  Either the reason that the ability to use literal IP addresses and
port numbers makes things easier for UBM senders is that forcing the use of
domain names is a non-trivial hurdle for message store owners to overcome, and
therefore is something that senders might like a way of avoiding in situations
where it is not worth the effort (such as a small organisation's internal mail
system, for example); or message store owners will not find it onerous to have
to use, and to publish data about, domain names and therefore this doesn't
really affect UBM senders at all and doesn't open up an avenue for greater
abuse.  

Who agrees with Charles that the option to specify an explicit list of IP
address and port number pairs in notifications should go into Room 101 ?