[Dovecot] cannot update mailbox - unable to lock for exclusive access

[Stan Hoeppner]

On 11/8/2012 2:29 AM, 1st WebDesigns wrote:
> Hi there,
> 
> We're using Dovecot version 1.0.7 and Postfix, and since upgrading our
> Linux box we're getting this in the maillog:

1.0.7 is absolutely ancient and no longer officially supported.  You
need 1.2.x minimum, 2.x.x even better.  And you say you just recently
upgraded your Linux distro?  What planet do you live on son?  You're a
few light years behind current stable software.

> Nov  8 07:49:11 server1 postfix/local[27901]: 04B8E7081DA:
> to=<xyz at xyz.com>, orig_to=<abc at abc.com>, relay=local, delay=19,
> delays=0.07/0/0/19, dsn=4.2.0, status=deferred (cannot update mailbox
> /var/spool/mail/abc for user abc. unable to lock for exclusive access:
> Resource temporarily unavailable)

The simple permanent fix to Postfix/Dovecot mbox locking issues is
switching from Postfix LOCAL to Dovecot LDA for mailbox delivery.  1.0.7
is before my time.  I do not know if LDA was available then.  Upgrade
and you'll have it, and you'll also fix other problems you're not even
aware of yet.

> Postfix is currently set to:
> mailbox_delivery_lock = fcntl, dotlock
> 
> Dovecot has this:
> mbox_read_locks = fcntl
> mbox_write_locks = fcntl dotlock

LDA completely eliminates lock contention.

http://wiki.dovecot.org/LDA/Postfix
http://wiki2.dovecot.org/LDA/Postfix

-- 
Stan