Re: [Exim] Refuse connection if no MX for sending host

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Συντάκτης: Tony Finch
Ημερομηνία:  
Προς: Exim Users Mailing List
Υ/ο: Tony Finch, Greg A. Woods
Αντικείμενο: Re: [Exim] Refuse connection if no MX for sending host
On Thu, Oct 23, 2003 at 10:33:53AM -0400, Greg A. Woods wrote:
>
> > Note also that it would be wrong to have an MX for plum.csi.cam.ac.uk
> > since there are no valid email addresses @plum.csi.cam.ac.uk.
>
> That's wrong. There is always at least one valid mailbox address at
> every mail server that answers and speaks SMTP on port 25 (and it _must_
> be valid for both the host name of the mailer as well as for a domain
> expressed as a literal IP address).


Well, according to RFC 2821, section 4.5.1:

Any system that includes an SMTP server supporting mail relaying or
delivery MUST support the reserved mailbox "postmaster" as a case-
insensitive local name. This postmaster address is not strictly
necessary if the server always returns 554 on connection opening (as
described in section 3.1). The requirement to accept mail for
postmaster implies that RCPT commands which specify a mailbox for
postmaster at any of the domains for which the SMTP server provides
mail service, as well as the special case of "RCPT TO:<Postmaster>"
(with no domain specification), MUST be supported.

We are in full compliance with this paragraph. We do not support address
literals despite the requirement in RFC1123; you might think this is
evil bad and wrong, but I don't care. We do not support email delivery
to arbitrary machines, and do not have to.

> There _should_ always be an MX for every domain name that is a host name
> of a mailer, and the target name of the MX should be the same domain
> name:


Where does it say that?

Tony.
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