Mail Records

Re: Mail Records

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On 07/02/01 at 12:12, Sean Stephens wrote:

> I'm not REALLY getting it, even after reading all of "DNS and BIND".
>
> For MX records, QDNS support had me change all my DNS records to look like
> this (which required everyone changing over from using a POP server of
> "test.com" to a new one called "mail.test.com");
>
> test.com. A 1.1.1.1
> test.com. MX 10 mail.test.com.
> test.com. MX 20 mail2.test.com.
> mail.test.com. A 1.1.1.2
> mail2.test.com. A 1.1.1.3
>
> This is for 3 separate computers, a web server (1.1.1.1), a mail server
> (1.1.1.2) and a secondary mail server (1.1.1.3).
>
> 1) Why not set up an MX record like this?
>
> test.com. MX 10 1.1.1.2

The data portion of an MX record (the right-hand side) should be a hostname,
not an IP address. Also, hosts listed as mail exchangers must have address (A)
records (DNS & BIND, 3rd ed., pg. 97).

> Is there any way to route MX requests from a domain (test.com.) to the
> authoritative mail domain (mail.test.com.), so people don't have to remember
> the mail host but can use their own domain as POP server?

MX records are used by SMTP mail exchangers, not POP clients (POP isn't a mail
exchange protocol, it's a delivery protocol, and it doesn't use MX records).
POP clients can use any domain name that resolves to your POP server.

> 2) If I DO set everything up so that every host goes to "mail.test.com.", do
> I need to set up anything on the primary mail server (like hosts or
> forwarding)?

The mail exchanger on mail.test.com needs to be configured so that it knows
it's supposed to accept mail for local delivery that's addressed to whatever
domains use it as their MX. Exactly how you do that depends on the particular
mail server you're using.

> 3) What do I need to set up on the secondary server (mail2.test.com.)? Do I
> need to set up everyone's email addresses? Do I need to set up mail hosts or
> set up forwarding? What makes it keep the emails until the primary
> (mail.test.com.) starts working again? Can clients GET the email from the
> secondary email server, or is it just a stop-gap until the primary comes
> back online?

Again, the exact configuration of the secondary mail server depends on what
server you're using, but it should be fairly simple and the docs for the mail
server should have info on using it as a secondary server. Basically, you just
need to tell the secondary that it should forward mail for the appropriate
domains to the primary server. You shouldn't need to create duplicate user
accounts on it. Your users will still retrieve their mail from the primary --
the secondary is a back-up for SMTP. If you want to set something up as a
'fail-over' back-up for POP or IMAP, it would be a bit more complicated
because you'd have to mirror the users' mailboxes between the primary and
secondary servers.

> Is there somewhere on the Men and Mice page with a description of an "ideal
> setup" and explanations as to why this claim is made?
>
> I really appreciate the feedback...
>
> Sean

Christopher Bort | cbort@globalhomes.com
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