Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!ucsd!ucbvax!McMaster.CA!WHITESID
From: WHITESID@McMaster.CA (Fred Whiteside)
Newsgroups: comp.protocols.tcp-ip
Subject: RE: re: MX Records
Message-ID: <90Apr9.131358edt.58407@ugw.utcs.utoronto.ca>
Date: 9 Apr 90 16:22:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 35

Christian Huitema <huitema@jerry.inria.fr> writes:

>  If the host has an A record, then the host is reachable directly via
>  the Internet. If one does not want to list that host as the MXer of
>  highest preference, it is probably that one does not want to receive
>  mail directly on that system, but rather feed the mail through some
>  "central" server. Indeed, there might be some good reasons for that,
>  like not wanting to receive mail directly on a PC.. BUT!!

        Invalid assumption. I have several machines which are directly
on the network that _cannot_ process SMTP (the two that spring to mind
are VMS vaxen with Bridge communications IVECS boards. These things
look like DMF's to the Vax and process the TCP Telnet on the board).
These machines want mail, but they *must* have it delivered via a
decnet channel. The MX forwarders for these machines understand this
so it all works.

>  Rather than prohibiting mailers to look at A records, Philip should
>  rather consider cleaning his own house, and not advertise the
>  addresses of PC or work stations as valid mail addresses!

        I can envision a scenario where I have seen an ftp connection
from some machine to my site and I want to send mail to
root@thatmachine for some logical reason. I reverse-lookup the IP
address and send mail to POSTMASTER@TheLooked-upAddress. The machine
may be a PC which won't handle inbound TCP connections and thus I
should have an MX record for the machine that points to a mailer that
Knows What To Do.

        The MX records are there for a good reason. Let's use them
properly. A records are host addresses. MX records are where you want
the mail delivered. It's quite simple.

-Fred Whiteside
 McMaster PostMaster, DNS Maintainer and Guy Who Worries About Such Things