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

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Author: Exim User's Mailing List
Date:  
To: Philip Hazel
CC: Russell King, Exim User's Mailing List
Subject: Re: [Exim] Domain literals: weighing up the arguments
[ On Tuesday, December 9, 2003 at 10:14:48 (+0000), Philip Hazel wrote: ]
> Subject: Re: [Exim] Domain literals: weighing up the arguments
>
> On Mon, 8 Dec 2003, Russell King wrote:
>
> > Since my MTA does not provide mail service for the domain [myrelaymtaip],
> > but does for "mydomain", where it accepts postmaster as a local part,
> > and it accepts <postmaster> on its own, I believe that I'm fully
> > compliant with this RFC section.
>
> That's a good description of the way I have always understood this.


No, it's totally bogus.

You cannot look at this issue from one direction only.

You must consider the implications of how some other mailer might
possibly be convinced to route a message to your mail server using your
mail server's IP address in a domain literal form and you must consider
how that mailer will present the recipient address to your mailer.

The recipient address <postmaster@[literal]> must be treated identicaly
to the unqualified <postmaster> address -- i.e. treated as a local
mailbox address. The same should apply to any other local mailbox
address, but of course <postmaster> is the most critical one, and the
one that _must_ be supported.

I.e. any domain part given in the form of a literal IP address, where
the address is (one of) the address(es) the MTA listens for connects on
port #25, always "exists" and is valid since it is simply an alternat
expression of the local host's own identity.

--
                        Greg A. Woods


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