backup mail server

Barry Margolin barmar at
Tue Oct 30 21:52:59 UTC 2001

In article <9rn73v$15k at>, phrogg <fake at> wrote:
>I'm trying to set up a backup mail server.  However, either I don't know how
>it works (in action), the mail server is broken, or I didn't do the DNS
>correctly.  This is what I have in my zone file:
>;system mail server
>  MX 10 mail
>  MX 20 mail2
>mail  CNAME @

MX records should not point to CNAME records.  So either change this line
to an A record, or change the first MX record to:

  MX 10 @

>mail2  A
>From what I understand about how email servers work, they first determine
>the MX records.  My dns server would return the addresses for "mail" and
>"mail2".  Then the mail server would try to deliver to the address at "mail"
>then, if that fails, the address at "mail2", since it has a higher
>preference value.  When I shut down my mail server (located at "mail"), and
>have someone send a test email, it gets bounced back to them, instead of
>being sent to the address at "mail2".

Did you allow enough time for your old MX record to expire from caches?

>So, my question is this: are my dns records set up properly?  Is there more
>I need to do?  I'm trying to narrow down by eliminating what's right so I
>can figure out what's wrong.

Other than the CNAME issue, which shouldn't cause the problem you're
having, it looks fine.

What's your domain?

Barry Margolin, barmar at
Genuity, Woburn, MA
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

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