IM2000 RNASP -- identifying message stores to recipients

In Jonathon's current definition of the Recipient Notification Agent
Submission Protocol [1], the recipient is told something along the lines of
"You have a message of approximately X bytes from sender <foo> to recipient
<bar>.  You can pick it up using identifier <baz> from <ServiceLocation>".

ServiceLocation is the bit that I'm wondering about.  It's identified as 0 or
more domain names and/or 0 or more IP address/port numbers (IPv4 or IPv6).  If
this is a domain name, I presume the intent is to have the recipient perform
an SRV DNS lookup to obtain an address/port combination -- that's good.  It
would be easy to publish a list of such domain names to avoid (known spam
operations, etc).

Address/port literals in the notification would seem to be a bit odd.  The
notifications are intended to be the most lightweight part of the protocol,
and having them direct recipients to "anonymous" IP addresses and port numbers
would seem to be a potential source of problems.  I might be missing
something, but I don't see the need for this.  What was the intent here?

Charles

[1] See http://homepages.tesco.net/~J.deBoynePollard/Proposals/IM2000/Architecture/rnasp.html
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Charles Cazabon                           <[email protected]>
GPL'ed software available at:     http://www.qcc.ca/~charlesc/software/
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