Newsgroups: comp.mail.sendmail
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!van-bc!ubc-cs!newsserver.sfu.ca!ian
From: ian@newsserver.sfu.ca (Ian Reddy)
Subject: Mail distribution via sendmail.mx confusion
Message-ID: <1991Apr29.235753.2639@newsserver.sfu.ca>
Keywords: sendmail mx dns 
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Mon, 29 Apr 91 23:57:53 GMT
Lines: 46

Okay, I'm crying "uncle". I just don't see how to do the following with
MX records:

    		Rest of the World (aka "Internet")
    				|
    				|
    mailserver.sfu.ca. (ie. central mailhost for Simon Fraser University)
    1) aka whistler.sfu.ca.
    2) has in DNS:
    	sfu.ca.		IN	MX	10	whistler.sfu.ca.
    	whistler.sfu.ca. IN	MX	10	whistler.sfu.ca.
    3) handles ultimately ALL incoming and outgoing mail for the campus
    4) does allow some (sub)domains (ie. chem.sfu.ca) or hosts
       (ie. charm.chem.sfu.ca) to receive/send mail as long as 3) is
       obeyed (here is the problem part).
       |			|			|
       |			|			|
    chem.sfu.ca.	charm.chem.sfu.ca.	blah.blah.sfu.ca.


       ^			^			^
       |			|			|
--> What do I put in the DNS for these hosts' MX records?????
    If I put in (for example):

    charm.chem.sfu.ca.	IN	MX	5	charm.chem.sfu.ca.
    charm.chem.sfu.ca.	IN	MX	10	whistler.sfu.ca.

    then incoming mail for charm will be delivered straight to charm
    rather than through whistler and if I put in:

    charm.chem.sfu.ca.	IN	MX	10	whistler.sfu.ca.
    charm.chem.sfu.ca.	IN	MX	15	charm.chem.sfu.ca

    then whistler will discard both entries and suffer an "internal
    error".


    There must be a way to have a central mailhost for a site as far
    as incoming mail is concerned and yet still allow for distribution
    within the site to subsidiary hosts. What am I missing?
-- 
Ian Reddy, UNIX Systems Consultant          Internet:  Ian_Reddy@ucs.sfu.ca
Computing Services, AD1021                  BITNET:    USERIGR1@SFU
Simon Fraser University                     Telephone: (604) 291-3936
Burnaby, B.C. Canada V5A 1S6                Fax:       (604) 291-4242