Comment 0 for bug 1519331

Every now and then postfix installed on my laptop stops delivering mails. I detect this problem after wandering about no answers to my emails, or by checking the current mail queue, which should be empty when I am at the office.

I use postfix to deliver all sent mail to the company SMTP server. The local postfix does not receive outside mail.

The mail queue shows errors of the type:

(Host or domain name not found. Name service error for name=XXXXXXXX type=AAAA: Host not found, try again)

When I manually check host name resolution, it works fine. It seems, postfix either does not retry name resolution, or somehow name resolution fails for postfix, but not other programs. Network connectivity is fine when this problem occurs (I read my mail via IMAP w/o local message body cache from the same server used as smart host, use SSH to other hosts, and surf the web -- I never noticed network problems when the postfix mail delivery did not work).

To remedy the situation I can just restart postfix and flush the mail queue. But I need to detect the problem, and postfix should™ recover on its own.

I am using IPv6 privacy extensions (Ubuntu default) in a dual stack IPv4 and IPv6 network. Both local (company) and remote servers are accessible via IPv6, thus I am actively using IPv6 for many connections. I have no idea if this is related to the problem, but the error shows a failure to resolve a quad A record.

Mandatory information:
1)
$ lsb_release -rd
Description: Ubuntu 14.04.3 LTS
Release: 14.04

2)
$ apt-cache policy postfix
postfix:
  Installed: 2.11.0-1ubuntu1
  Candidate: 2.11.0-1ubuntu1
  Version table:
 *** 2.11.0-1ubuntu1 0
        500 http://ftp.uni-kl.de/pub/linux/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     2.11.0-1 0
        500 http://ftp.uni-kl.de/pub/linux/ubuntu/ trusty/main amd64 Packages

3)
I expected postfix to deliver the queued mail. If there was a (temporary, perhaps very short) network problem, postfix should recover automatically after the problem was resolved.

4)
Postfix stopped delivering mails.