Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!computer-science.nottingham.ac.UK!j.onions
From: j.onions@computer-science.nottingham.ac.UK (Julian Onions)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Host requirements and SMTP
Message-ID: <27168.631550427@cs.nott.ac.uk>
Date: 5 Jan 90 14:40:27 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 38


Craig, thanks for the reply - it clears up most of the points.

> > Section>  5.2.17 
> > Urgghhhhh! This is awful. Making this a MUST is horrible. [I waffle on]..

> Gee -- that's what we tried to do, only a bit more forcefully.  Domain
> literals may show up, your mailer must not barf on them, and if the
> domain literal = your host, your mailer ought to accept it.  In other
> words, God help us, should you get a domain literal, do the minimum
> rational thing -- don't fail, and swallow it if it is for you.

Having to deal with them at all is the problem. The bit that grates on
me is half way through parsing the address you have to suddenly fly
off and discover what all your current IP numbers are. In an otherwise
faily portable bit of software such as an address parser, suddenly
having to dig down into the depths of the currently configured
interfaces is ugly. IP addresses have no place at the mail address
parsing level.

I can now sort of see the rationale behind them. From reading the HR
spec, I sort of imagined (rightly or wrongly) that the debate went
something like:
  "Look, its a really useful debugging technique to send direct to IP
  addresses, so lets force everyone to handle d-lits and debugging
  becomes a lot easier. We can even source route using IP addresses
  then if required."
I would still prefer that you MUST be able to parse the construct but
that you MAY ignore them and can bounce a message if it requires
understanding them.

I think the reason for my unease is that the HR are pretty strong on
discouraging source routing. The d-lit section doesn't say they are
discouraged, just that you must be able to parse them and recognise
your own - which sounds more like encouragement of their use.
Inserting your text above would really show what was meant!

Julian.