Re: [Exim] Domain literals: weighing up the arguments

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Auteur: Russell King
Datum:  
Aan: Exim User's Mailing List
Onderwerp: Re: [Exim] Domain literals: weighing up the arguments
On Wed, Dec 10, 2003 at 02:18:02PM -0500, Greg A. Woods wrote:
> If you'd bother to read and try to understand what I've written
> repeatedly in some valiant attempt to make this extremely clear to you,
> you would already have known that I am not trying to mandate anything
> even remotely close to that.


It is /you/ who have consistently not read what I'm saying. Go back to
square one and start again with this thread, and you'll see what I'm
/actually/ saying, not what you think I'm saying.

You appear to believe that I'm saying that "postmaster@domain" should
not be valid; indeed, you're quoting bits of an obsoleted standard
which describe the necessary need to mandatorily supply such an
address.

However, if you look at the /current/ standard, RFC2822, you'll realise
that the address "postmaster" is also mandated, a point which you've
missed by looking at out of date standard information.

Note: for clarity, I'll say this: I'm not saying that postmaster
addresses are optional. They /are/ required. Period. We're in
agreement, ok?

> RFC 821 (August, 1982):


Again, another obsoleted standard. Try looking up RFC2821 at some
point, just to make sure you have the /current/ information to hand.

> [[ ... reordered and summarized to show just the relevant syntax ... ]]
>
>             RCPT <SP> TO:<forward-path> <CRLF>

>
>             <forward-path> ::= <path>

>
>             <path> ::= "<" [ <a-d-l> ":" ] <mailbox> ">"

>
>             <mailbox> ::= <local-part> "@" <domain>

>
>             <domain> ::=  <element> | <element> "." <domain>

>
>             <element> ::= <name> | "#" <number> | "[" <dotnum> "]"


So, "domain" can be "foo.bar.baz" or "[ipliteral]", etc. Nothing new
here.

However, /nothing/ that you have quoted says that "you must provide
postmaster@[ipliteral]".

Yes, sure, if you provide mail service for a domain @[ipliteral] then
the standards mandate that you have postmaster@[ipliteral]. However,
if you don't provide service for the domain [ipliteral], they do not
mandate that address.

Moreover, what I also said earlier was that /if/ you want to mandate
postmaster@[ipliteral], then you should seek to get it through the
internet standard procedures and placed into one of these documents
so you can quote it at people.

Now, link this up with the comment that the /reason/ people want
postmaster@[ipliteral] to work is in case of a misbehaving SMTP
server, when, eg, the DNS is down. Now consider the case that the
misbehaving SMTP server does not accept mail from the public internet,
but is sending you mail, yet the DNS is down. Sending mail to
postmaster@[thathostsipliteral] just won't work.

See my point?

If not, please, don't bother replying, because I doubt you'll /ever/
understand the subtlety of my argument.

--
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core