Linux Mailserver down – how to reinstall libs used by Postfix?

I have a new issue, unable to send/receive mail on a Lenny based Postfix/Dovecot/MySql setup.

Syslog shows Apr 4 11:09:21 Debian-50-lenny-64-LAMP postfix/master[19796]: warning: /usr/lib/postfix/smtpd: bad command startup -- throttling
Apr 4 11:09:21 Debian-50-lenny-64-LAMP kernel: [17525916.163351] smtpd[19804]: segfault at 1000000 ip 7f2284c6983a sp 7fff74240960 error 6 in libresolv-2.13.so[7f2284c60000+13000]

I believe symptoms may have started after removing Avahi-Daemon but not certain, reinstalling it certainly hasn’t helped.
Using apt is there a way I can reinstall the libs used by postfix, i.e. above libresolv-2.13.so looks to be the cause, but again I’m not certain.

The output of ‘top’ shows this kworker really eating up processing time which I think is what the logs show is being throttled.

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
14364 root 20 0 77268 10m 508 S 399 0.0 85969:00 [kworker]

Any suggestions most welcome!
Thanks,

Answer

To answer my own question:

In the syslog I can see the offending library was libresolv-2.13.so – yet in /var/spool/postfix/lib all the libs were version 2.7 and there was no libresolv in there. Doing a locate libresolv I found there were 2 versions present, the 2.13 and also a 2.7 version.
Once I made sure postfix was using the 2.7 version, and restarted it, smtpd was working again.

Attribution
Source : Link , Question Author : Dave , Answer Author : Dave

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