'Domain not found' errors after Ubuntu upgrade

[Y z]

After a large upgrade of many packages on Ubuntu Karmic, postfix has stopped working properly. Symptoms:

lost of
postfix/smtpd[5922]: warning: 224.90.55.65.bl.spamcop.net: RBL lookup error: Host or domain name not found. Name service error for name=224.90.55.65.bl.spamcop.net type=A: Host not found, try again

and, on every message coming in, rejection:
postfix/smtpd[5916]: NOQUEUE: reject: RCPT from unknown[65.55.90.236]: 450 4.1.8 <***@hotmail.com>: Sender address rejected: Domain not found; from=<***@hotmail.com> to=<recipient-***@mungeddomain.invalid> proto=ESMTP helo=<snt0-omc4-s33.snt0.hotmail.com>

dig and nslookup work from the command prompt, both as root and a non-privileged user.

As far as I can tell, I am not running chroot-ed.

Postfix version is 2.6.5; I'll post postconf -n if it helps.

Where do I start troubleshooting?

Thanks!

Thanks!
 


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[Stan Hoeppner]

Post by Y z
Where do I start troubleshooting?

Start by making sure that these match:

/etc/resolv.conf
/var/spool/postfix/etc/resolv.conf

When cli dns tools work, that usually means the first file above is correct,
fsvo "correct". When postfix can't resolve dns, it usually means the second
file's contents have changed since it was working previously.

Your files might be in slightly different locations depending on your OS,
but you get the general idea of what you need to look for.

Hope this helps, and is timely. Sounds like you're in a pinch.

[Stan Hoeppner]

Post by Stan Hoeppner

Post by Y z
Where do I start troubleshooting?

/etc/resolv.conf
/var/spool/postfix/etc/resolv.conf
When cli dns tools work, that usually means the first file above is correct,
fsvo "correct". When postfix can't resolve dns, it usually means the second
file's contents have changed since it was working previously.
Your files might be in slightly different locations depending on your OS,
but you get the general idea of what you need to look for.
Hope this helps, and is timely. Sounds like you're in a pinch.

Forgot to mention: restart Postfix after making the change or it won't take
effect. A reload might work also but I'm not sure. Best to go with a
restart. On many systems, and specifically Debian/Ubuntu, as root:

~$ /etc/init.d/postfix restart

[Y z]

----------------------------------------

Date: Wed, 28 Apr 2010 01:56:55 -0500
Subject: Re: 'Domain not found' errors after Ubuntu upgrade

Post by Stan Hoeppner

Post by Y z
Where do I start troubleshooting?

/etc/resolv.conf
/var/spool/postfix/etc/resolv.conf

Yup. Postfix start warns me if they differ.
I tried putting in nameservers  there, but that makes it worse: then postfix (it's supposed to relay) accepts the messages, then can't find te relay domain, so it bounces them. Ouch.

Post by Stan Hoeppner
When cli dns tools work, that usually means the first file above is correct,
fsvo "correct". When postfix can't resolve dns, it usually means the second
file's contents have changed since it was working previously.
Your files might be in slightly different locations depending on your OS,
but you get the general idea of what you need to look for.
Hope this helps, and is timely. Sounds like you're in a pinch.

Forgot to mention: restart Postfix after making the change or it won't take
effect. A reload might work also but I'm not sure. Best to go with a
~$ /etc/init.d/postfix restart

Yup. Been starting and stopping for a while now. :-(

--
Stan

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[Uwe Dippel]

Post by Y z

Post by Stan Hoeppner

Post by Stan Hoeppner
/etc/resolv.conf
/var/spool/postfix/etc/resolv.conf

Yup. Postfix start warns me if they differ.
I tried putting in nameservers there, but that makes it worse: then postfix (it's supposed to relay) accepts the messages, then can't find te relay domain, so it bounces them. Ouch.

Post by Stan Hoeppner
~$ /etc/init.d/postfix restart

Yup. Been starting and stopping for a while now. :-(

I had something similar a few days back, when - duh - all my incoming
mail got stuck for the same reason. I knew about the two resolv.conf,
but nothing helped.
Then I tried some dig another.domain.com MX, and it timed out, while dig
another.domain.com didn't. Once name resolution of MX was back, postfix
was back after a restart. I dunno, if it was a bad coincidence, though I
didn't like it all too much.

Good luck,

Uwe

[Y z]

----------------------------------------

Date: Wed, 28 Apr 2010 15:20:08 +0800
Subject: Re: 'Domain not found' errors after Ubuntu upgrade

Post by Y z

Post by Stan Hoeppner

Post by Stan Hoeppner
/etc/resolv.conf
/var/spool/postfix/etc/resolv.conf

Yup. Postfix start warns me if they differ.
I tried putting in nameservers there, but that makes it worse: then postfix (it's supposed to relay) accepts the messages, then can't find te relay domain, so it bounces them. Ouch.

Post by Stan Hoeppner
~$ /etc/init.d/postfix restart

Yup. Been starting and stopping for a while now. :-(

I had something similar a few days back, when - duh - all my incoming
mail got stuck for the same reason. I knew about the two resolv.conf,
but nothing helped.
Then I tried some dig another.domain.com MX, and it timed out, while dig
another.domain.com didn't. Once name resolution of MX was back, postfix
was back after a restart. I dunno, if it was a bad coincidence, though I
didn't like it all too much.
Good luck,
Uwe

I'm sure (well, almost sure) that bind got hosed *somehow*. Postfix really doesn't have more than a bit part in this drama. I just want to figure out why Postfix gets different answers than dig at the command prompt. Lack of sleep doesn't help. :-)



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[Stan Hoeppner]

Post by Y z
----------------------------------------

Date: Wed, 28 Apr 2010 01:56:55 -0500
Subject: Re: 'Domain not found' errors after Ubuntu upgrade

Post by Stan Hoeppner

Post by Y z
Where do I start troubleshooting?

/etc/resolv.conf
/var/spool/postfix/etc/resolv.conf

Yup. Postfix start warns me if they differ.
I tried putting in nameservers there, but that makes it worse: then postfix (it's supposed to relay) accepts the messages, then can't find te relay domain, so it bounces them. Ouch.

I've only ever had this name resolution problem once and that's how I solved
it, with hints from this list.

Post by Y z
Yup. Been starting and stopping for a while now. :-(

Did you check nsswitch.conf for 'dns' under 'hosts'?

Something broke Postfix' ability to resolve dns. It's not complaining about
a library version error, which points to configuration only. Make sure
SELinux is _not_ enabled. Turn off any iptables rules you have loaded.

[Uwe Dippel]

Post by Y z
I'm sure (well, almost sure) that bind got hosed *somehow*. Postfix
really doesn't have more than a bit part in this drama. I just want to
figure out why Postfix gets different answers than dig at the command
prompt.

Relax.
I am sure you did
dig that.other.mail.org MX.
Then the answer can't be different among postfix and command prompt.
If the two resolv.conf are identical. If need be (and some will jump
into my face) our little helper is 'cp' for identical results (and
resolvers) to get some mails delivered as long as the resolution on the
command line is satisfying. (That's what I did on Monday morning when
the queue was overflowing and the dreaded warning about them being
different came up. Luckily, here 'cp' worked.)

And I still have the desire to understand, why the resolvers could
become different over the weekend; when the name resolution(s) for MX
failed. I can't believe 'because of' the MX reolution(s) failed, and
yet/var/spool/postfix/etc/resolv.conf was just empty.
'Restart' had not helped. Only when the resolution was back, would the
two be identical again. Very strange.

Uwe