[comp.mail.sendmail] How serious is the at->@ problem?

emv@math.lsa.umich.edu (Edward Vielmetti) (11/09/89)

In article <7867@ditmela.oz> smart@ditmela.oz.au (Robert Smart) writes:
>I know that names ending in .at (i.e. Austria) have caused problems
>with at->@ mail rewriting rules. I have recently commented out at->@
>from our sendmail.cf for this reason. By coincedence the Australia
>Telescope would like to set up their computers as machine.at.csiro.au.
>The question is: is an "at" in the middle of a domain name like that
>likely to cause problems with broken mailer software around the place?
>I would particularly like to hear from anybody else who has a ".at."
>in their domain name (or in a domain name they know about).

There's an 'at.man.ac.uk' at an astronomy department in Manchster,
which triggered my awareness of the problem.  You might want to
ask them as well.

I'd discourage them (sigh) unless you're willing to send out a lot of
mail on their behalf to people (like me right now, sigh) who have
said broken mailers.  Not much mail goes to Austria yet, and there's
no ridiculously popular service or person there, so chances are this
at->@ bug is still in a good many sendmail.cf's.

--Ed (at this point making a patch for my sendmail.cf's....)

Edward Vielmetti, U of Michigan math dept

roy@phri.UUCP (Roy Smith) (11/10/89)

In article <7867@ditmela.oz> smart@ditmela.oz.au (Robert Smart) writes:
> The question is: is an "at" in the middle of a domain name like that
> likely to cause problems with broken mailer software around the place?

	I correspond with somebody at psuvm.bitnet.  I often get mail from
him with headers that look like the following.  Note the "AT" in the
In-Reply-To: line.  I doubt this would every cause any problems as all the
"real" addresses are in standard @ format.

----------------
Received: from PSUVM.BITNET by uccvm.nyu.edu (IBM VM SMTP R1.2) with BSMTP id 4110; Fri, 15 Sep 89 17:20:31 EST
To: roy@alanine.phri.nyu.edu
In-Reply-To:  roy AT alanine.phri.nyu.edu -- Fri, 15 Sep 89 09:33:14 EDT
----------------
-- 
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
{att,philabs,cmcl2,rutgers,hombre}!phri!roy -or- roy@alanine.phri.nyu.edu
"The connector is the network"

clarke@acheron.uucp (Ed Clarke/10240000) (11/12/89)

> In article <7867@ditmela.oz> smart@ditmela.oz.au (Robert Smart) writes:
> The question is: is an "at" in the middle of a domain name like that
> likely to cause problems with broken mailer software around the place?
>

I'm not sure, but will this fix the problem?  It's from the IBM AIX sendmail.cf.
This seems to imply that the 'at' must have whitespace on both sides of it to be
processed into a '@'.

#
#  Turn an "at" token into "@".
#
#  The I macro specifies space or some equivalent char defined by the OI
#  config option above.
#
R$+$Iat$I$+             $:$1@$2                         "at" -> "@" for RFC 822

-- 
Ed Clarke
acheron!clarke

marcl@vax.SPD.3Com.Com (Marc Lavine) (11/15/89)

In article <1989Nov11.171244.28119@acheron.uucp> clarke@acheron.uucp (Ed Clarke/10240000) writes:
>I'm not sure, but will this fix the problem?  It's from the IBM AIX
>sendmail.cf.  This seems to imply that the 'at' must have whitespace
>on both sides of it to be processed into a '@'.
>
>#
>#  Turn an "at" token into "@".
>#
>#  The I macro specifies space or some equivalent char defined by the OI
>#  config option above.
>#
>R$+$Iat$I$+             $:$1@$2                         "at" -> "@" for RFC 822

I believe that the proper fix for the munging of "at" to "@" is to
remove all code that performs this action.  RFC 822 states:

     C.5.5.  AT-SIGN

        The string " at " no longer is used as an  address  delimiter.
        Only at-sign ("@") serves the function.

Hence "at" is obsolete and there's no need to support it unless you have
to process mail that is in RFC 733 format.  The configuration files
distributed with the copy of sendmail 5.6.1 that I have do not convert
"at" to "@" and in my opinion, neither should yours.
-- 
Marc Lavine			Old Internet: marcl%3Com.Com@sun.com
Smart: marcl@3Com.Com		UUCP: ...{sun|decwrl}!3comvax!marcl

dan@ccnysci.UUCP (Dan Schlitt) (11/18/89)

In article <10116@stag.math.lsa.umich.edu> emv@math.lsa.umich.edu (Edward Vielmetti) writes:
:In article <7867@ditmela.oz> smart@ditmela.oz.au (Robert Smart) writes:
:>I know that names ending in .at (i.e. Austria) have caused problems
:>with at->@ mail rewriting rules. 
	[text deleted]
:>The question is: is an "at" in the middle of a domain name like that
:>likely to cause problems with broken mailer software around the place?
:
:There's an 'at.man.ac.uk' at an astronomy department in Manchster,
:which triggered my awareness of the problem.  You might want to
:ask them as well.
:
:I'd discourage them (sigh) unless you're willing to send out a lot of
:mail on their behalf to people (like me right now, sigh) who have
:said broken mailers.  Not much mail goes to Austria yet, and there's
:no ridiculously popular service or person there, so chances are this
:at->@ bug is still in a good many sendmail.cf's.
:
I have also noticed problems with hosts (or subdomains) the same as
the two letter national codes.  Some sendmail.cf files look for these
and assume the terminal part is just added junk and strip it.  Not
right but it evidently is out there.

:--Ed (at this point making a patch for my sendmail.cf's....)
:
:Edward Vielmetti, U of Michigan math dept


-- 
Dan Schlitt                        Manager, Science Division Computer Facility
dan@sci.ccny.cuny.edu              City College of New York
dan@ccnysci.uucp                   New York, NY 10031
dan@ccnysci.bitnet                 (212)690-6868

asjl@tinakori.comp.vuw.ac.nz (Andy Linton) (11/23/89)

:There's an 'at.man.ac.uk' at an astronomy department in Manchster,
:which triggered my awareness of the problem.

These people are really asking for trouble. In the UK, the powers that
be for reasons unfathomable to me decided that host addresses should be
written back to front WRT the rest of the world e.g. my address in UK
format is: 

	Andy.Linton@nz.ac.vuw.comp

Sendmail and other mailers used in the UK have large chunks of their
config files taken up with changing RFC822 domain based names into the
UK "Grey Book" order and vice versa. You can see what's going to happen
with the Manchester address. If the MTA decides it's in "Grey Book"
format it should go to Austria but if the MTA decides it's RFC822 then
reverse the order and send to a UK host. But wait a minute this could be
a message for Austria written in RFC822 order etc etc.

I know the JNT won't get their act together now on the naming scheme in
the UK as they are committed to X.400 but the guys at manchester could
do themselves a favour in two ways by changing their machine name.
--
SENDER = Andy Linton
EMAIL  = Andy.Linton@comp.vuw.ac.nz	PHONE = +64 4 721 000 x8978

jim@cs.strath.ac.uk (Jim Reid) (11/24/89)

In article <1989Nov23.001545.750@kaukau.comp.vuw.ac.nz> Andy.Linton@comp.vuw.ac.nz writes:
>:There's an 'at.man.ac.uk' at an astronomy department in Manchster,
>:which triggered my awareness of the problem.

... Explanation of Britain's perverse use of different domain ordering
... from the rest of the world deleted.

>I know the JNT won't get their act together now on the naming scheme in
>the UK as they are committed to X.400 but the guys at manchester could
>do themselves a favour in two ways by changing their machine name.

Strictly speaking, Manchester's astronomers have registered a semi- illegal
name. You are not allowed to register a domain name that is already used
as a higher-level domain name. If the .at domain was registered in the
British name scheme (it isn't - sigh), 'at.man.ac.uk' would be illegal.

		Jim

dell@amelia.nas.nasa.gov (Thomas E Dell) (11/25/89)

>Strictly speaking, Manchester's astronomers have registered a semi- illegal
>name. You are not allowed to register a domain name that is already used
>as a higher-level domain name. If the .at domain was registered in the
>British name scheme (it isn't - sigh), 'at.man.ac.uk' would be illegal.

This cannot be enforced, mainly because of the .us domain. Witness the
.il.us <=> .il Israel, .ca.us <=> .ca Canada, and .net.com <=> .net, among
other examples.

It does pose an interesting dilemma to DNS software run in the 
offending domains. My guess is that it will only be a problem if/when 
.ca.us and .ca both achieve large Internet populations.

                 ...Tom

dell@ames-nas.arpa | Abolish velcro before it's too late..

bill@twwells.com (T. William Wells) (11/26/89)

: >Strictly speaking, Manchester's astronomers have registered a semi- illegal
: >name. You are not allowed to register a domain name that is already used
: >as a higher-level domain name. If the .at domain was registered in the
: >British name scheme (it isn't - sigh), 'at.man.ac.uk' would be illegal.

Frankly, I don't believe this. It implies that one who assigns a
higher level domain name be aware of all lower level domain names
-- even those not in his domain. This is inconsistent with my
understanding of the rationale of the domain name system.

Someone care to quote chapter and verse?

---
Bill                    { uunet | novavax | ankh | sunvice } !twwells!bill
bill@twwells.com

rayan@cs.toronto.edu (Rayan Zachariassen) (11/26/89)

>>You are not allowed to register a domain name that is already used
>>as a higher-level domain name. If the .at domain was registered in the
>>British name scheme (it isn't - sigh), 'at.man.ac.uk' would be illegal.

>It does pose an interesting dilemma to DNS software run in the 
>offending domains. My guess is that it will only be a problem if/when 
>.ca.us and .ca both achieve large Internet populations.

As I recall, it used to be DNS policy (stated in one of the early RFCs)
that within a host one could default domain names by a sliding match (first
common subdomain) on one's own domain name.  For example, if your host was
foo.sf.ca.us you could use glob.la.ca as a shorthand for glob.la.ca.us.
It was always stated that all names leaving a system should be fully qualified.

This policy was one of the major arguments in the CA vs. CA.US battle.

About the time the ISO codes got popular and country-level domains were
getting registered, Mockapetris denounced this mechanism.  There is no
requirement that toplevel domains don't appear at lower levels, its just
good practise to avoid it when possible.

The scheme lives on in the present DNS resolvers, but the sliding window
matching isn't quite the same and it usually stops at the organizational
boundary anyway.

As for ' at ', dealing with that shouldn't be the job of an RFC822 mailer,
it should be done by a protocol translation program.

rayan