qmail alert: cannot start: unable to open mutex

For some reason the mail log was showing lots of:

Sep 23 09:40:03 hostname qmail: 1253695203.637058 alert: cannot start: unable to open mutex
Sep 23 10:32:16 hostname qmail: 1253698336.515510 alert: cannot start: unable to open mutex
Sep 23 10:32:21 hostname qmail: 1253698341.425333 alert: cannot start: unable to open mutex

and qmail was not working properly.

It turns out that for some reason /var/qmail/queue/lock/ was missing along with the file /var/qmail/queue/lock/sendmutex.  Had to recreate these with:

[[email protected] ~]# mkdir /var/qmail/queue/lock/
[[email protected] ~]# chown qmailq:qmail /var/qmail/queue/lock/
[[email protected] ~]# touch /var/qmail/queue/lock/sendmutex
[[email protected] ~]# chown qmails:qmail /var/qmail/queue/lock/sendmutex

Then qmail would start fine.

URL:

rblsmtpd 451 Sender has sent to LashBack

Bounce message received:

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

[email protected]

Malformed SMTP reply from mail.server.com [192168.1.1]
in response to initial connection:
rblsmtpd: 192.168.6.62 pid 14483: 451 Sender has sent to LashBack
Unsubscribe Probe accounts:
retry timeout exceeded

Looking further into this it appears that the sending IP address was listed in a RBL black list.  The RBL server being queried was: ubl.unsubscore.com

This in turn (www.unsubscore.com) took me to: http://www.lashback.com/support/UnsubscribeBlacklistSupport.aspx

Most RBL systems return a useful message with a URL, but, not lashback.