MX records

[Mark Damrose]

"Ted Wood" <twood at twu.edu> wrote in message
news:a6tleu$hgb at pub3.rc.vix.com...
>
> I've got a question about MX records.  My domain, twu.edu, has a mail
server
> which has an A record which points to just the domain name like so:
> @ IN A 205.165.49.231
> It is also the preferred mail server:
> @ IN MX 0 venus.twu.edu
> And of course it also has its own A record:
> venus IN A 205.165.49.232
>
> There are also some other mail servers with lower preference values:
> @ IN MX 10 exchange.twu.edu
> @ IN MX 20 vulcan.twu.edu
> etc.
>
> Now, as I understand MX records, mail sent to somebody at twu.edu should try
> venus first, then exchange, then vulcan.  However, if somebody at twu.edu has
> their account on exchange or vulcan, the mail never gets there.  If I send
> it to somebody at exchange.twu.edu or somebody at vulcan.twu.edu it gets there.
> Why isn't this working?

Multiple MX records are for availability.  If venus is *down* it will try
exchange, and if exchange is down too, it will try vulcan.  If venus is up
and not configured to accept mail for users on exchange or vulcan - the mail
will be rejected.

*All 3 machines need to know how to deliver mail for users on the others,
and queue it if necessary*
How to do this is a MTA issue and not a DNS issue.  Good luck.

Is it because of this record: @ IN A
> 205.165.49.231?  It seems to be that since twu.edu points to a particular
> IP, mailers are just looking it up directly and not even looking for the
MX
> records.  Thanks in advance for any help.
> Ted Wood
>