Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!ucsd!ucsdhub!hp-sdd!hplabs!hpda!hp-sde!hpfcdc!hpfclp!diamant
From: diamant@hpfclp.SDE.HP.COM (John Diamant)
Newsgroups: comp.mail.sendmail
Subject: Re: Re: mixed addresses
Message-ID: <1410007@hpfclp.SDE.HP.COM>
Date: 19 Jul 88 05:09:21 GMT
References: <8807142016.dusip.andrew@stl.stc.co.uk>
Organization: HP SDE, Fort Collins, CO
Lines: 46

> You have brought up a nasty.  In fact you are highlighting two
> of them.  Firstly '%' as an address character.  IT IS NOT LEGAL RFC822.
> It remains around for historical compatibility (RFC7?? --- read the
> first page of 822 if you really want to know which).

It is also not illegal RFC822.  It is legal as part of the local-part,
but can only be interpreted by the destination machine.  It would probably
be wrong for any gateway to interpret it in that light.

> Having got that off my chest, here is the associated nasty:  mcvax
> uses it as a 'local-part' operator, and hands on addresses of the form
> a!b!u%l, which any Internetted (and probably any JANET) host will treat
> as send to 'l' for uucp forwarding.  UK1.? will resolve it as
> @l,@a:u@b (using 822 legal representation), on the assumption that
> the % constitutes a mal-formed domain address. 

Sorry, that's not more legal (RFC822 explicitly states that only registered
domain addresses may be listed in the components of a source route --
presumably the hosts in your example are not registed domain addresses).

> UNDER NO CIRCUMSTANCES OTHER THAN MAINTAINING YOUR NEIGHBOURS MAIL
> ROUTER CAN YOU ASSUME ANYTHING WHATSOEVER ABOUT THE PRIORITY HE WILL
> PLACE ON THE VARIOUS SYMBOLS.  The only safe and reasonable course
> to take is to provide the destination address in the format required
> by the network you are using.

That's not as safe or reasonable as you might think.  It isn't always
possible to convert to the local routing format given the restrictions in
RFC822 (source routes only valid for registered domains, "%" only interpretable
in local part, not real routing character).  What happens when you take a
"!" route and try to convert it to the 822 world -- do you use "%" or
source routing -- both have problems?

> Now if only the whole world would get it's act together and magically
> supply domain based mailers to everyone...

Yes, this would be nice.  Then we have to get you guys on JANET to use
the same ordering for your domains as everyone else.  I don't think one
ordering is inherently better than any other, but, frankly, you're
outnumbered, and "standard is better than better."


John Diamant
Software Development Environments
Hewlett-Packard Co.		ARPA Internet: diamant@hpfclp.sde.hp.com
Fort Collins, CO		UUCP:  {hplabs,hpfcla}!hpfclp!diamant