Applying Dovecot for a large / deep folder-hierarchy archive.

[Arnold Opio Oree]

Hello Aki,

Thank you greatly for your advice, it is really valuable to know that
the key criteria for our desired application of Dovecot are
supported (our groupware stacks are running Dovecot 2.3.4.1) prior to
commencing operations to configure Dovecot and migrate enterprise data.

Thanks for the word of caution with regards to mbox format; that was a
slip of the tongue on my part, our groupware stacks are using Maildir
format (I will also look into sdbox as I had not been aware of it as a
viable alternative), although we have yet to change the LAYOUT to fs - which I think should be better for meeting our deep directory criteria, and also for managing mailbox data directly in the filesystem (please do let me know if you think otherwise).

The only areas of uncertainty for me now are whether Dovecot will be
able to change directory layout to fs where emails are already held in
user mailboxes with Maildir++ directory layout; and secondly what the
best protocol will be to get the Outlook PST data into the Dovecot
mailbox. I will research these points, if however there is any best
practice that you are aware of, then it will be great to know.

Very best,

Arnold Opio Oree
Chief Executive Officer
Parallax Digital Technologies

arnoldoree at parallaxdt.com

http://www.parallaxdt.com

tel : +44 (0) 333 577 8587
fax : +44 (0) 20 8711 2477

Parallax Digital Technologies is a trading name of Parallax Global
Limited. U.K. Co. No. 08836288

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-----Original Message-----
From: Aki Tuomi via dovecot <dovecot at dovecot.org>
Reply-To: Aki Tuomi <aki.tuomi at open-xchange.com>
To: arnoldoree at parallaxict.com, Arnold Opio Oree <
arnold.oree at parallaxict.com>, Dovecot Mailing List <dovecot at dovecot.org
>
Subject: Re: Applying Dovecot for a large / deep folder-hierarchy
archive.
Date: Thu, 27 Jun 2019 08:35:17 +0300

On 26.6.2019 22.12, Arnold Opio Oree via dovecot wrote:
> Hello to you all,
> 
> I'd like to ask about my intended application of Dovecot to create a
> folder-hierarchy for storing our enterprise emails, which are treated
> as live data rather than archives for compliance or occasional /
> reactive retrieval.
> 
> The data is presently not that large (a few gigabytes), but it is
> expected to grow rapidly. Up to this stage the data has been
> contained
> in a Microsoft Exchange mailbox (2013), and then in an offline PST.
> The move to the offline PST was by necessity, as the large number of
> folders, and depth of hierarchy to my best understanding caused the
> exchange server / outlook / evolution mail clients to begin to
> malfunction. To cope with this the archive was broken up and the bulk
> stored in the offline PST and the most active components stored in
> online Exchange mailboxes.
> 
> I have some understanding of the fs mbox format, and also the
> mitigations to be made for certain characters / strings. My main
> concern is whether Dovecot is likely to be able to cope well with a
> large number of folders / depth of hierarcy.
> 
> I will really appreciate any help / advice you can give.
> 
> Best regards,
> 
> Arnold Opio Oree
> 

Hi!

Dovecot 2.2.34/2.3 supports unlimited folder depth, the only limiting
factor is that the total name may not exceed 4096 bytes. Also
individual
folder names may not exceed 255 bytes.

Prior to that the limit is 255 per folder up to 16 levels.

I can't recommend using 'mbox' storage format, please consider using
maildir or sdbox instead.

Aki