ietf-smtp
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Re: nullmx

2008-03-31 15:33:07


Mark Andrews wrote:

It doesn't however mean you cannot send mail from that
machine however. You just have to set an appropriate mail
domain for outgoing mail.

Rather than toster(_at_)toaster(_dot_)example(_dot_)net the mail would come
from tosterXXX(_at_)example(_dot_)net or something similar if you
were using "MX 0 .".

JFTR, that is a nullmx for toaster.example.net, and the host
toaster.example.net can send MAIL FROM tosterXXX(_at_)example(_dot_)net
(or from almost any address excluding @toaster.example.net).

Mail to <postmaster> at this host is still supposed to work.

Say what? That's only the case if the host runs an SMTP server, in which case
it is entirely logical to require support of a postmaster address. It is
entirely possible for a host to have an SMTP client and no server.

In fact the language is even more restrictive - postmaster is only required for
servers that perform delivery or relay functions. I presume that's so a stub
server that always returns 5xy errors isn't required to accept postmaster mail. 

I couldn't tell without cheating (= looking into 2821bis) if
that's MUSTard, SHOULD, or between the lines.

It isn't even between the lines as far as I can tell. If you believe otherwise
you'll need to cite the relevant sections of 2821bis to support your point. I
couldn't find anything along the lines of what you appear to be claiming in
there.

                                Ned