[Dovecot] zlib config questions

Richard Platel rplatel at tucows.com
Fri Dec 6 17:55:18 EET 2013

You only need to add the zlib plugin to mail_plugins once.

As far as I know, there's no indication in the logs that mail is being compressed, and the filename isn't modified to indicate that it's compressed, but, of course, the files are zlib data on disk.

One gotcha if you're using maildir is, if you're planning to compress old mail, make sure that the S= and W= sizes in the filenames are correct, otherwise dovecot errors and closes the client session, and it can't repair the filename on it's own.

On Dec 6, 2013, at 12:51 AM, dovecot-request at dovecot.org wrote:

> Message: 6
> Date: Thu, 5 Dec 2013 13:55:40 -0800
> From: Terry Barnum <terry at dop.com>
> To: Dovecot Mailing List <dovecot at dovecot.org>
> Subject: [Dovecot] zlib config questions
> Message-ID: <EF7F46D0-DE03-4B11-85ED-D669DE78D931 at dop.com>
> Content-Type: text/plain; charset=us-ascii
> After nearly running out of space I swapped in larger disks and then saw the recent threads about zlib compression. Unfortunately I'm still confused after reading <http://wiki2.dovecot.org/Plugins/Zlib>.
> In order to compress new email being stored do I only need to change
> 10-mail.conf to this:
> mail_plugins = $mail_plugins zlib
> and 90-plugin.conf to this:
> plugin {
>  zlib_save_level = 6
>  zlib_save = gz
>  ...
> Or do I need to instead (or also?) add it to the list of plugins in 20-imap.conf?
> A simple 'sudo doveadm reload' to enable?
> Once enabled, is there an indication in the logs that compression is taking place?
> Do new mail files have a suffix like .Z to indicate they've been compressed?
> Any gotchas to be aware of? 
> I'm running macports dovecot 2.2.5.
> Thanks for any help.
> -Terry
> Terry Barnum
> digital OutPost
> http://www.dop.com

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