On Dec 17, 2007, at 12:45 PM, Charles Curley wrote:

On Mon, Dec 17, 2007 at 10:52:45AM -0700, Shane Hathaway wrote:
Charles Curley wrote:
I set up bind9 on an Ubuntu box several weeks ago. Now, email on two
Ubuntu machines is broken. I get, e.g.

Dec 17 09:50:58 phoenix postfix/smtp[436]: 08D2A16A0E4:
to=<[EMAIL PROTECTED]>, orig_to=<root>, relay=none, delay=8152,
delays=8142/0.01/10/0, dsn=4.4.3, status=deferred (Host or domain
name not found. Name service error for name=charlesc type=A: Host not
found, try again)

This should work once "dig mx charlesc" works on 192.168.1.3. Postfix
looks first for an MX record rather than an A record.

It does? I've never had an MX record before. And failing an MX record,
shouldn't it then try for an A record?

Yes. Er, well, that's how the RFC says it should work. A quick glance at the postfix source confirms that it does work this way. :)

From RFC 2821:
"The lookup first attempts to locate an MX record associated with the name. If a CNAME record is found instead, the resulting name is processed as if it were the initial name. If no MX records are found, but an A RR is found, the A RR is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host. If one or more MX RRs are found for a given name, SMTP systems MUST NOT utilize any A RRs associated with that name unless they are located using the MX RRs; the "implicit MX" rule above applies only if there are no MX records present."

-peter

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