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

[1st WebDesigns]

> So this is a step in the right direction.  But still far less than
> optimal.  The read/write lock contention on mbox is unnecessarily eating
> up system resources (mainly memory), and causing unnecessary delivery
> delays to the mailbox.  You should really start looking at migrating to
> maildir.  It's not that difficult (though maybe more so with 1.0.7) if
> you don't have a ton of mailboxes, and especially with POP since the
> mailboxes typically wont be holding much mail to migrate.  How many do
> you have?

There's around four hundred mail boxes or so.  Some used more 
intensively than others.

>
>> Our server is with Rackspace, and RHEL5 is the OS they offered us as an
>> upgrade path from RHEL4.  So they're getting the support from Red Hat
>> and we're getting the support from Rackspace.
>
> The plot thickens again.  You're using a rented server.  Sigh...
>
> This entire thread could have been greatly shortened, saving all of us
> much time, if you'd have given all these details up front.
>
> Is this a cloud server (shared host), or a dedicated server?

It's a dedicated server

>
> FWIW, you don't have RHEL5, but CentOS 5.  Hosting companies don't pay
> for RHEL licenses for 10s of thousands of hosts.

It's RHEL5:

$cat /etc/issue
Red Hat Enterprise Linux Server release 5.8 (Tikanga)

The cost of the license is included in our contract.

>
> I have a few salient recommendations for you:
>
> 1.  Migrate to maildir.  It is far more appropriate for a POP workload.

Yes, this will be our next course of action

> 2.  Switch to a hosting provider that offers much more recent software.

We can upgrade the software if we wish, but will no longer get full 
support from Rackspace if we do this.

> 3.  Or, get a colo server so you can use whatever software you wish.

We can install whatever software we wish at the moment, but see the 
point above.

>
> Finally, if this email service you're providing isn't all that critical
> to you or your organization, simply prod along as you have been,
> fighting these problems frequently along the way.
>

It's kind of working ok now but we will go with your recommendation of 
switching to maildir when we have time.  Thanks for your help