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

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Arnold Opio Oree

26 Jun 2019 26 Jun '19

7:12 p.m.

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 containedin a Microsoft Exchange mailbox (2013), and then in an offline PST. The move to the offline PST was by necessity, as the large number offolders, and depth of hierarchy to my best understanding caused the exchange server / outlook / evolution mail clients to begin tomalfunction. To cope with this the archive was broken up and the bulk stored in the offline PST and the most active components stored inonline 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 OreeChief Executive OfficerParallax Digital Technologies arnoldoree@parallaxdt.com

http://www.parallaxdt.com

tel : +44 (0) 333 577 8587fax : +44 (0) 20 8711 2477 Parallax Digital Technologies78A Hatfeild MeadLondonSM4 5PF Parallax Digital Technologies is a trading name of Parallax GlobalLimited. U.K. Co. No. 08836288 The contents of this e-mail are confidential. If you are not theintended recipient you are to delete this e-mail immediately, disregardits contents and disclose them to no other persons.

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Aki Tuomi

27 Jun 27 Jun

5:35 a.m.

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

Arnold Opio Oree

10:42 a.m.

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@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

...

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

Aki Tuomi

10:44 a.m.

If you change layout to FS you are basically required to migrate users to it. You cannot change layout "on the fly".

Aki

On 27.6.2019 13.42, Arnold Opio Oree via dovecot wrote:

...

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@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Aki Tuomi via dovecot dovecot@dovecot.org Reply-To: Aki Tuomi aki.tuomi@open-xchange.com To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com>, Dovecot Mailing List
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

Arnold Opio Oree

10:48 a.m.

...

If you change layout to FS you are basically required to migrate users to it. You cannot change layout "on the fly".

Duly noted.

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

From: Aki Tuomi via dovecot dovecot@dovecot.org Reply-To: Aki Tuomi aki.tuomi@open-xchange.com To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com>, Dovecot Mailing List

...

Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 27 Jun 2019 13:44:25 +0300

If you change layout to FS you are basically required to migrate users to it. You cannot change layout "on the fly".

Aki

On 27.6.2019 13.42, Arnold Opio Oree via dovecot wrote:

...

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@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Aki Tuomi via dovecot < dovecot@dovecot.org

...
Reply-To: Aki Tuomi < aki.tuomi@open-xchange.com

...
To: arnoldoree@parallaxict.com , Arnold Opio Oree < arnold.oree@parallaxict.com

...
, Dovecot Mailing List < dovecot@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

Robert Schetterer

10:53 a.m.

Am 27.06.2019 um 07:35 schrieb Aki Tuomi via dovecot:

...

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

Also you may run into client limits.... i ve seen this with outlook, apple mail, thunderbird via imap in the past

-- [*] sys4 AG

https://sys4.de, +49 (89) 30 90 46 64 Schleißheimer Straße 26/MG,80333 München

Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer, Wolfgang Stief Aufsichtsratsvorsitzender: Florian Kirstein

Arnold Opio Oree

11:05 a.m.

...

Also you may run into client limits.... i ve seen this with outlook, apple mail, thunderbird via imap in the past

Thanks for this note Robert, it was not really an aspect that I was considering.

We are operating our groupware services user access through both Evolution Groupware and KDE Kontact / KMail on Debian Linux workstations. Hopefully if there is a client issue it should be local to only one groupware client.

I will be sure to study / investigate in this - client - area should any issues that are not traceable to the server-side arise.

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Robert Schetterer via dovecot dovecot@dovecot.org Reply-To: Robert Schetterer rs@sys4.de To: dovecot@dovecot.org Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 27 Jun 2019 12:53:49 +0200

Am 27.06.2019 um 07:35 schrieb Aki Tuomi via dovecot:

...

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

Arnold Opio Oree

4 Jul 4 Jul

1:52 p.m.

Hi all,

The guidance provided so far has been really helpful, and has helped a great deal to bringing down wasted energy on finding and executing a viable path. I am now at the final due action to complete our Dovecot application to our use-case, but am stuck on an issue that I cannot find any easily accessible documentation on.

Generally this is what has been done:

Uploaded the enterprise data PST to the target groupware server.
Prepared the server by changing the mailbox format to sdbox and the the Dovecot mail location to mail_location=/var/vmail/domain/user/mail/
Converted the pst (on-server) to a recursive mbox hierarchy using readpst
Executed doveadm-sync to convert mbox hierarchy data into sdbox and to copy it into the enterprise archive user's mailboxes 4.i. The biggest issue I faced at this point was doveadm-sync saying that the source and destination pointed to the same location, whereas they clearly did not. 4.i.a. I resolved this by removing the location= setting from the target namespace, and allowing it to default to mail_location = setting, and then using a completely different DIRNAME for the import doveadm-sync execution (which was the desired final DIRNAME); I then once the sync had been successful, changed the mail_location DIRNAME so that it pointed to the imported mail DIRNAME; and hence the imported email data was in the live mailboxes 4.i.b. doveadm-import failed several times, and was throwing quite inexplicable errors, so I moved onto doveadm-sync 4.i.c. I also had to make sure that the source and destination folder names matched, otherwise doveadm-syc threw very many errors and only partially imported the data 4.i.d. An issue which I decided just to live with is that an mbox DIRNAME was added to each mailbox as well as the DIRNAME specified so the path to mail is mbox/dbox-Mails. My thought is that with the data live on an IMAP server it will be possible to do a dysync through TCP to correct this problem.

The final issue that I am facing now, is that when readpst finds empty folders in the source pst hierarchy, it does not create an mbox file in the mbox hierarchy folder space. This causes doveadm-sync to not create the target data required for its mailbox structure i.e. DIRNAME sub- folder and index file (with our configuration). At this point either doveadm-sync or the dovecot process makes these empty folders not selectable.

The question now is how would I go about making all of these folders selectable, e.g. with an internal or external command line tool to change flags / create necessary sdbox mailbox constituent data?

-----Original Message----- From: Arnold Opio Oree via dovecot dovecot@dovecot.org Reply-To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com> To: Robert Schetterer rs@sys4.de, dovecot@dovecot.org Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 27 Jun 2019 12:05:35 +0100

...

Also you may run into client limits.... i ve seen this with outlook, apple mail, thunderbird via imap in the past

Thanks for this note Robert, it was not really an aspect that I wasconsidering. We are operating our groupware services user access through bothEvolution Groupware and KDE Kontact / KMail on Debian Linuxworkstations. Hopefully if there is a client issue it should be localto only one groupware client. I will be sure to study / investigate in this - client - area should any issues that are not traceable to the server-side arise. Many thanks, Arnold Opio OreeChief Executive OfficerParallax Digital Technologies arnoldoree@parallaxdt.com

http://www.parallaxdt.com

tel : +44 (0) 333 577 8587fax : +44 (0) 20 8711 2477 Parallax Digital Technologies is a trading name of Parallax GlobalLimited. U.K. Co. No. 08836288 The contents of this e-mail are confidential. If you are not theintended recipient you are to delete this e-mail immediately, disregardits contents and disclose them to no other persons.

-----Original Message-----From: Robert Schetterer via dovecot < dovecot@dovecot.org>Reply-To: Robert Schetterer rs@sys4.deTo: dovecot@dovecot.org Subject: Re: Applying Dovecot for a large / deep folder- hierarchyarchive.Date: Thu, 27 Jun 2019 12:53:49 +0200 Am 27.06.2019 um 07:35 schrieb Aki Tuomi via dovecot:

...

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 createa folder-hierarchy for storing our enterprise emails, which aretreated as live data rather than archives for compliance oroccasional / reactive retrieval. The data is presently not that large (a few gigabytes), but it isexpected to grow rapidly. Up to this stage the data has beencontainedin a Microsoft Exchange mailbox (2013), and then in an offline PST.The move to the offline PST was by necessity, as the large numberoffolders, and depth of hierarchy to my best understanding caused theexchange server / outlook / evolution mail clients to begin tomalfunction. To cope with this the archive was broken up and thebulk stored in the offline PST and the most active componentsstored inonline Exchange mailboxes. I have some understanding of the fs mbox format, and also themitigations to be made for certain characters / strings. My mainconcern is whether Dovecot is likely to be able to cope well with alarge 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 limitingfactor is that the total name may not exceed 4096 bytes. Alsoindividualfolder 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 usingmaildir or sdbox instead. Aki

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

Arnold Opio Oree

7 Jul 7 Jul

3:12 p.m.

New subject: Applying Dovecot for a large / deep folder-hierarchy archive - BUG REPORTS!

Dovecot Team,

I'd like to report a number of bugs, that are to my view all critical.

System: Replicated on multiple Debian 10 (Buster) systems Dovecot Version(s): 2.3.4.1

doveadm-sync -1/general

If DIRNAMEs are not different between command line and mail_location doveadm sync will fail, saying that the source and destination directories are the same
The -n / -N flags do not work, and a sync will fail strangely if location is specified in the namespace definition
Adds mbox to path name under mailbox directory (where syncing from an mbox source)
Not having the mailboxes at source named the same as those at destination causes errors and partial sync
Not having the target mailboxes formatted to receive the sync (/<mailboxroot>/DIRNAME/) will cause sync errors.

doveadm-sync

With large synchronizations UIDs are corrupted where multiple syncs are executed and the program can no longer synchronize

dovecot

Panics and fails to expand ~ to user home: observed cases are where multiple namespaces are being used

Please let me know if you need me to elaborate or to provide any further information that you may need to replicate the bugs, or if I can help in any other way.

With regards to the last error that I requested help on i.e. \Noselect. This has been resolved more-or-less by the workarounds that I have implemented for the bugs reported above.

I have seen a number of threads whilst researching the \Noselect issue where people have been very confused. My finding was that \Noselect is a function of the IMAP specification server-side implementation RFC3501 (https://tools.ietf.org/html/rfc3501#section-6.3.6). And for me the server was returning directories with \Noselect because the mailboxes were malformed on account of dovadm-sync errors. In order to fix this I formed a bash command to transverse the mailbox hierarchy and create the missing folders critical to the sdbox format, namely DIRNAME.

Kind regards,

Arnold Opio Oree

-----Original Message----- From: Arnold Opio Oree via dovecot dovecot@dovecot.org Reply-To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com> To: dovecot@dovecot.org Cc: rs@sys4.de, aki.tuomi@open-xchange.com Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 04 Jul 2019 14:52:28 +0100

Hi all,

Generally this is what has been done:

Uploaded the enterprise data PST to the target groupware server.
Prepared the server by changing the mailbox format to sdbox and the the Dovecot mail location to mail_location=/var/vmail/domain/user/mail/
Converted the pst (on-server) to a recursive mbox hierarchy using readpst
Executed doveadm-sync to convert mbox hierarchy data into sdbox and to copy it into the enterprise archive user's mailboxes 4.i. The biggest issue I faced at this point was doveadm-sync saying that the source and destination pointed to the same location, whereas they clearly did not. 4.i.a. I resolved this by removing the location= setting from the target namespace, and allowing it to default to mail_location = setting, and then using a completely different DIRNAME for the import doveadm-sync execution (which was the desired final DIRNAME); I then once the sync had been successful, changed the mail_location DIRNAME so that it pointed to the imported mail DIRNAME; and hence the imported email data was in the live mailboxes 4.i.b. doveadm-import failed several times, and was throwing quite inexplicable errors, so I moved onto doveadm-sync 4.i.c. I also had to make sure that the source and destination folder names matched, otherwise doveadm-syc threw very many errors and only partially imported the data 4.i.d. An issue which I decided just to live with is that an mbox DIRNAME was added to each mailbox as well as the DIRNAME specified so the path to mail is mbox/dbox-Mails. My thought is that with the data live on an IMAP server it will be possible to do a dysync through TCP to correct this problem.

The question now is how would I go about making all of these folders selectable, e.g. with an internal or external command line tool to change flags / create necessary sdbox mailbox constituent data?

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

...

Also you may run into client limits.... i ve seen this with outlook, apple mail, thunderbird via imap in the past

Thanks for this note Robert, it was not really an aspect that I was considering.

I will be sure to study / investigate in this - client - area should any issues that are not traceable to the server-side arise.

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Robert Schetterer via dovecot < dovecot@dovecot.org

...

Reply-To: Robert Schetterer < rs@sys4.de

...

To: dovecot@dovecot.org

Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 27 Jun 2019 12:53:49 +0200

Am 27.06.2019 um 07:35 schrieb Aki Tuomi via dovecot:

...

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

-- Dear [Recipient],

[Content]

Regards,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@parallaxdt.com

http://www.parallaxdt.com

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

Parallax Digital Technologies 78A Hatfeild Mead London SM4 5PF

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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons. Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

Aki Tuomi

8 Jul 8 Jul

5:48 a.m.

New subject: Applying Dovecot for a large / deep folder-hierarchy archive - BUG REPORTS!

Arnold Opio Oree

12:21 p.m.

New subject: Applying Dovecot for a large / deep folder-hierarchy archive - BUG REPORTS!

Hello Aki,

Thanks for looking into these.

I will as requested attempt the relevant procedures under Dovecot 2.3.6.

To make the test fair, I will need to fork the relevant production groupware stack (which is now stable and in operation, with our enterprise (email) data successfully migrated from Microsoft Exchange) to a new staging server; given that the current staging server is now of a materially different configuration to the production server (where the most controlled observations of these bugs were made).

Kindly give me some time, as I have an urgent internal openstack deployment project to kick-off, that has been delayed by an overrun of this internal groupware stack deployment project.

Best regards,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Aki Tuomi via dovecot dovecot@dovecot.org Reply-To: Aki Tuomi aki.tuomi@open-xchange.com To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com>, Arnold Opio Oree via dovecot < dovecot@dovecot.org> Cc: debian-release@lists.debian.org Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive - BUG REPORTS! Date: Mon, 8 Jul 2019 08:48:08 +0300 (EEST)

Hi!

Thank you for reporting these. We will look into them. In the mean time, can you see if any of these are fixed in 2.3.6?

Aki

...

On 07/07/2019 18:12 Arnold Opio Oree via dovecot
...
wrote:

Dovecot Team,

I'd like to report a number of bugs, that are to my view all critical.

System: Replicated on multiple Debian 10 (Buster) systems Dovecot Version(s): 2.3.4.1

doveadm-sync -1/general

If DIRNAMEs are not different between command line and mail_location doveadm sync will fail, saying that the source and destination directories are the same

The -n / -N flags do not work, and a sync will fail strangely if location is specified in the namespace definition

Adds mbox to path name under mailbox directory (where syncing from an mbox source)

Not having the mailboxes at source named the same as those at destination causes errors and partial sync

Not having the target mailboxes formatted to receive the sync (/<mailboxroot>/DIRNAME/) will cause sync errors.

doveadm-sync

With large synchronizations UIDs are corrupted where multiple syncs are executed and the program can no longer synchronize

dovecot

Panics and fails to expand ~ to user home: observed cases are where multiple namespaces are being used

Please let me know if you need me to elaborate or to provide any further information that you may need to replicate the bugs, or if I can help in any other way.

With regards to the last error that I requested help on i.e. \Noselect. This has been resolved more-or-less by the workarounds that I have implemented for the bugs reported above.

I have seen a number of threads whilst researching the \Noselect issue where people have been very confused. My finding was that \Noselect is a function of the IMAP specification server-side implementation RFC3501 ( https://tools.ietf.org/html/rfc3501#section-6.3.6). And for me the server was returning directories with \Noselect because the mailboxes were malformed on account of dovadm-sync errors. In order to fix this I formed a bash command to transverse the mailbox hierarchy and create the missing folders critical to the sdbox format, namely DIRNAME.

Kind regards,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Arnold Opio Oree via dovecot < dovecot@dovecot.org> Reply-To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com> To: dovecot@dovecot.org Cc: rs@sys4.de, aki.tuomi@open-xchange.com Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 04 Jul 2019 14:52:28 +0100

Hi all,

The guidance provided so far has been really helpful, and has helped a great deal to bringing down wasted energy on finding and executing a viable path. I am now at the final due action to complete our Dovecot application to our use-case, but am stuck on an issue that I cannot find any easily accessible documentation on.

Generally this is what has been done:

Uploaded the enterprise data PST to the target groupware server.

Prepared the server by changing the mailbox format to sdbox and the the Dovecot mail location to mail_location=/var/vmail/domain/user/mail/

Converted the pst (on-server) to a recursive mbox hierarchy using readpst

Executed doveadm-sync to convert mbox hierarchy data into sdbox and to copy it into the enterprise archive user's mailboxes 4.i. The biggest issue I faced at this point was doveadm-sync saying that the source and destination pointed to the same location, whereas they clearly did not. 4.i.a. I resolved this by removing the location= setting from the target namespace, and allowing it to default to mail_location = setting, and then using a completely different DIRNAME for the import doveadm-sync execution (which was the desired final DIRNAME); I then once the sync had been successful, changed the mail_location DIRNAME so that it pointed to the imported mail DIRNAME; and hence the imported email data was in the live mailboxes 4.i.b. doveadm-import failed several times, and was throwing quite inexplicable errors, so I moved onto doveadm-sync 4.i.c. I also had to make sure that the source and destination folder names matched, otherwise doveadm-syc threw very many errors and only partially imported the data 4.i.d. An issue which I decided just to live with is that an mbox DIRNAME was added to each mailbox as well as the DIRNAME specified so the path to mail is mbox/dbox-Mails. My thought is that with the data live on an IMAP server it will be possible to do a dysync through TCP to correct this problem.

The final issue that I am facing now, is that when readpst finds empty folders in the source pst hierarchy, it does not create an mbox file in the mbox hierarchy folder space. This causes doveadm-sync to not create the target data required for its mailbox structure i.e. DIRNAME sub-folder and index file (with our configuration). At this point either doveadm-sync or the dovecot process makes these empty folders not selectable.

The question now is how would I go about making all of these folders selectable, e.g. with an internal or external command line tool to change flags / create necessary sdbox mailbox constituent data?

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Arnold Opio Oree via dovecot < dovecot@dovecot.org> Reply-To: arnoldoree@parallaxict.com, Arnold Opio Oree < arnold.oree@parallaxict.com> To: Robert Schetterer < rs@sys4.de>, dovecot@dovecot.org Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 27 Jun 2019 12:05:35 +0100

...
Also you may run into client limits.... i ve seen this with outlook, apple mail, thunderbird via imap in the past

Thanks for this note Robert, it was not really an aspect that I was considering.

We are operating our groupware services user access through both Evolution Groupware and KDE Kontact / KMail on Debian Linux workstations. Hopefully if there is a client issue it should be local to only one groupware client.

I will be sure to study / investigate in this - client - area should any issues that are not traceable to the server-side arise.

Many thanks,

Arnold Opio Oree Chief Executive Officer Parallax Digital Technologies

arnoldoree@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

The contents of this e-mail are confidential. If you are not the intended recipient you are to delete this e-mail immediately, disregard its contents and disclose them to no other persons.

-----Original Message----- From: Robert Schetterer via dovecot < dovecot@dovecot.org

...
Reply-To: Robert Schetterer < rs@sys4.de

...
To: dovecot@dovecot.org

Subject: Re: Applying Dovecot for a large / deep folder-hierarchy archive. Date: Thu, 27 Jun 2019 12:53:49 +0200

Am 27.06.2019 um 07:35 schrieb Aki Tuomi via dovecot:

...
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

Aki Tuomi

Timo Sirainen

10 Jul 10 Jul

8:09 a.m.

New subject: Applying Dovecot for a large / deep folder-hierarchy archive - BUG REPORTS!

On 7 Jul 2019, at 18.12, Arnold Opio Oree via dovecot dovecot@dovecot.org wrote:

...

Dovecot Team,

I'd like to report a number of bugs, that are to my view all critical.

It would help to get your doveconf -n, example command lines causing the problems and the error messages it outputs or what the wrong behavior looks like in filesystem. It's now rather difficult to guess what exactly you tried and what happened.

Also what kind of output does readpst make? I'm not sure why you're using DIRNAMEs here.

...

doveadm-sync -1/general

If DIRNAMEs are not different between command line and mail_location doveadm sync will fail, saying that the source and destination directories are the same

This sounds very strange. I'm not sure what exactly you did, and I couldn't reproduce with a small test.

...

The -n / -N flags do not work, and a sync will fail strangely if location is specified in the namespace definition

Again, sounds strange.

...

Adds mbox to path name under mailbox directory (where syncing from an mbox source)

Probably with different parameters you could avoid it.

...

Not having the mailboxes at source named the same as those at destination causes errors and partial sync

Not having the target mailboxes formatted to receive the sync (/<mailboxroot>/DIRNAME/) will cause sync errors.

I don't understand these. Target mailboxes are supposed to be empty initially, and after the initial sync they should be in the expected format. Why would they be different?

...

doveadm-sync

With large synchronizations UIDs are corrupted where multiple syncs are executed and the program can no longer synchronize

What exactly is the error message?

...

dovecot

Panics and fails to expand ~ to user home: observed cases are where multiple namespaces are being used

Panic message and more details would also help.

...

With regards to the last error that I requested help on i.e. \Noselect. This has been resolved more-or-less by the workarounds that I have implemented for the bugs reported above.

I have seen a number of threads whilst researching the \Noselect issue where people have been very confused. My finding was that \Noselect is a function of the IMAP specification server-side implementation RFC3501 ( http://h5lm.mjt.lu/lnk/AMwAAEPRQ68AAAAAAAAAAKAFynQAASKA_AUAAAAAAAf-tABdIgvzB...https://tools.ietf.org/html/rfc3501#section-6.3. http://h5lm.mjt.lu/lnk/AMwAAEPRQ68AAAAAAAAAAKAFynQAASKA_AUAAAAAAAf-tABdIgvzB...6). And for me the server was returning directories with \Noselect because the mailboxes were malformed on account of dovadm-sync errors. In order to fix this I formed a bash command to transverse the mailbox hierarchy and create the missing folders critical to the sdbox format, namely DIRNAME.

Nowadays we have also an option to disable creation of \Noselect folders, because they confuse people. Using mail_location = ...:NO-NOSELECT - It won't affect existing folders immediately though.

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List overview

11 comments

5 participants

participants (5)

Aki Tuomi
Arnold Opio Oree
Arnold Opio Oree
Robert Schetterer
Timo Sirainen