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From: drockwel@CSNET-SH.ARPA (Dennis Rockwell)
Newsgroups: net.mail.headers
Subject: Re: Domain names in the NIC table
Message-ID: <2214@brl-tgr.ARPA>
Date: Thu, 17-Oct-85 11:09:38 EDT
Article-I.D.: brl-tgr.2214
Posted: Thu Oct 17 11:09:38 1985
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	From: Postmaster + BITINFO <netinfo%ucbjade@ucb-vax.arpa>
	Date: Wed, 16 Oct 85 21:11:54 pdt
	Subject: Re: Domain names in the NIC table

	[ ... ]

	Prehaps we need a separate nameserver for mail domains, or away
	of indicating a domain name is not on the physical internet?

	Bill Wells

There already is: the domain servers for those hosts should set up MF
records pointing to the relay host that is on the Internet.  CSNET plans to
use this mechanism to support our hosts on PhoneNet (with the MF pointing to
RELAY.CS.NET aka CSNET-RELAY.ARPA).  Thus, people using resolvers can send
mail to, for instance, JoeStudent@Foo-U.EDU, and their mailer should ship
the message off to CSNET-RELAY.

This implies that everybody who is rewriting their mailers to use a resolver
should cause them to ask for type=MAILA records *first*, then type=A
records.  This way we can give the appearance of connectivity for mail hosts
not directly on the Internet.  Of course, this can used for UUCP, BITNET,
MAILNET and whoever else wants to do this.  Berkeley can put in an MF record
for, say ERNIE.BERKELEY.EDU, which points to BERKELEY.EDU, or whatever.

We (BBN) are considering using this mechanism to keep people from trying to
send mail to TACs (yes, it happens).  Our local TACs would have MF records
pointing to BBN-UNIX (aka UNIX.BBN.COM), but PTR and A records giving their
IP address, so that telnet servers can discover the name of the source of
new connections.

Let me repeat, because it's *important*: mailers should look for MAIL
records first, address records second.

Dennis Rockwell
CSNET Technical Staff