Switching directories from maildir to mbox in kmail 4.14.1

[rhkramer at gmail.com]

On Monday, May 20, 2019 02:46:17 PM Martin Steigerwald wrote:
> rhkramer at gmail.com - 19.05.19, 03:47:
> > On Saturday, May 18, 2019 09:18:57 PM rhkramer at gmail.com wrote:
> > > Background: For a period of time, I have to do some work on a Debian
> > > Jessie system.  The supported version of kmail is 4.14.1.  I've
> 
> An ancient version of KMail.

Newer than the one I've been using up to now (and, actually, continuing to 
use).  (kmail 1.13.7 on Debian Wheezy).

> Why would you need to switch them to mbox? Maybe there is another
> solution to the goal you like to accomplish.

I've spent a long time (I don't want to admit how long -- close to 18 years) 
building, essentially, a free format database (sort of an askSam workalike) 
using mbox as the basic framework.  I've got semi-working versions using kate 
as the editor, now working on building an editor based on scintilla -- very 
slow going.

I intend to allow records (essentially in the format of emails) to be 
intermixed with real emails in mbox files.

> > I should add that I've done some googling, and found some instructions
> > that seem to imply the when I create a new folder, I should get a
> > popup that has a selection for mbox or maildir.  That doesn't popup
> > on this system.
> 
> There are three resources for local mail storage:
> 
> 1. Maildir (default): stores mails in a maildir folder structure.
> 
> 2. Mbox: Accesses a single mailbox file (good for local mail in '/var/
> spool/mail').
> 
> 3. Mixedmaildir: allows to decide per folder whether to use maildir or
> mbox.
> 
> I bet the third would show up the popup you mentioned. However it has
> been a long time I last used it.
> 
> When you create a new user defined resource for receiving (and storing)
> mails I believe when you use 'KMail mail folder' (roughly translated
> from German) you will get mixedmaildir resource.

Hmm, I have no idea how to create "a new user defined resource for receiving 
(and storing) mails".  I've tried googling, and, so far, nothing makes sense 
to me.
 
> Please note tough: I migrated away since back then KDEPIM developers
> changed the default as well and wrote several times that they do not
> recommend using it anymore. It has a completely different implementation
> and since it is not the default anymore, it likely does not receive as
> much testing as before.
> 
> In general it should work, but on attempts to import a KMail mail folder
> resource folder into KDEPIM some years ago I saw a very high memory
> usage. I stopped the import which I triggered by creating a KMail mail
> resource pointing to that old folder due to intense swapping¹. It has
> been a long time ago and this issue may be fixed meanwhile. However you
> are using an ancient version of KMail and  I believe mixedmaildir
> resource did not receive much development work for a long time – so the
> bug may still be there. (Don't bother to reopen the bug report when it
> is still there in such an ancient version of KMail tough.)
> 
> The folder I tried to import contained only MBox folders I used for
> archival. Prior to removing the mixedmaildir resource before migrating
> to a newer version of KDEPIM/Akonadi back then, I created a new pure
> maildir resource and separated migrated all maildir folders to it so
> that the old mixedmail resource just contained mbox folders anymore.
> 
> I'd actually like to use the mixedmaildir thing again cause a folder of
> mbox folders is really nice to archive mails and still have them
> accessible within KMail. Cause rsync'ing a few mbox files that do not
> even change afterwards anymore to backup disk is much faster than
> rsync'ing millions of little mail files. For now I just tar maildir
> folders with huge mailing lists and then remove them afterwards from
> time to time to keep Akonadi performance above a certain level. At one
> point when computers and Akonadi have more performance I may re-import
> them by just un-tar-ing them into the right location within the maildir
> resource folder.
> 
> So or so I believe for KDEPIM/Akonadi developers there is more important
> work to do than to deal with any issues mixedmaildir resource may have.
> 
> 
> [Akonadi] [Bug 334318] New: on adding old mail archive mixedmaildir
> resource consumes tons of memory
> https://bugs.kde.org/show_bug.cgi?id=334318
> 
> Thanks,