dovecot - Jun 2020 - How to use dovecot only as POP3 server / prevent it from creating .imap directories?

On 08.06.2020 07:41, Joseph Tam wrote:
> On Sun, 7 Jun 2020, Binarus wrote:
> 
>> So how exactly do I have to alter the configuration to implement your
>> suggestion, i.e.? to make dovecot look only at the mbox file and to
>> prevent the creation of unnecessary directories?
> 
> Maybe try
> 
> ????mail_location = mbox:/empty/dir:INBOX=~/inbox
> 
> Not sure whether owner=rootZ:root, mode=555 will work, but those
> permissions would be the safest.
> 
Thank you very much for your suggestion. Actually, I already had tried
that, but that was only for testing, and I was hoping to avoid it.

Having said this:

That suggestion does not solve the problem completely, but reduces the
negative impact so much that I can live with it. I had tried

mail_location = mbox:~/mail:INBOX=~/mail/inbox

With that, dovecot still created an .imap subdirectory, but only within
the mail subdirectory in every user's home directory. The layout was the
following (starting in an arbitrary user's home directory, showing only
the contents of the mail subdirectory):

./mail/inbox
./mail/.imap
./mail/.imap/dovecot-uidvalidity
./mail/.imap/dovecot.list.index.log
./mail/.imap/dovecot-uidvalidity.5edce848
./mail/.imap/INBOX
./mail/.imap/INBOX/dovecot.index.log
./mail/.imap/INBOX/dovecot.index
./mail/.imap/INBOX/dovecot.index.log.2
./mail/.imap/INBOX/dovecot.index.cache

While there are no .imap subdirectories in other parts of the home
directories any more (which was the main goal), there are still at least
three unnecessary files plus one unnecessary directory with four
unnecessary files left. This is an ugly waste of resources, but it won't
keep me from going that way.

Obviously, dovecot is not meant to serve only POP3 any more (it used to
work in previous versions, where it didn't create .imap directories if
IMAP was disabled, if I remember correctly), but I don't know an
alternative. All other POP3 servers which are currently maintained which
I am aware of also have included an IMAP part, so I can probably expect
the same problems as with dovecot. Since I currently have no motivation
to learn another server software's configuration just to see that this
got me nowhere, I'll just stick with the solution outlined above and
hope that the POP3 part of dovecot will not be given up in the next
versions, and that dovecot does not go wild and start to create more and
more directories or files in unforeseeable manner.

The disadvantage of the solution above was that I had to reconfigure the
MTA (in this case, sendmail) to deliver inbound messages to ~/mail/inbox
instead of ~/inbox, which is another why I didn't implement this
solution immediately. At least, this was quite easy.

Thank you very much again!

Regards,

Binarus

On Tue, Jun 09, 2020 at 12:32:18 +0200, Binarus wrote:
...
> ./mail/inbox
> ./mail/.imap
> ./mail/.imap/dovecot-uidvalidity
> ./mail/.imap/dovecot.list.index.log
> ./mail/.imap/dovecot-uidvalidity.5edce848
> ./mail/.imap/INBOX
> ./mail/.imap/INBOX/dovecot.index.log
> ./mail/.imap/INBOX/dovecot.index
> ./mail/.imap/INBOX/dovecot.index.log.2
> ./mail/.imap/INBOX/dovecot.index.cache
> 
> While there are no .imap subdirectories in other parts of the home
> directories any more (which was the main goal), there are still at least
> three unnecessary files plus one unnecessary directory with four
> unnecessary files left. This is an ugly waste of resources, but it
won't
> keep me from going that way.
> 
> Obviously, dovecot is not meant to serve only POP3 any more
The .imap directory isn't really about IMAP.  It is sort of a generic
directory that just happens to have "imap" in the name.  The index
files you
see are required for various features inside dovecot to work properly.  Many
of them are related to performance rather than a specific protocol.
Granted, POP3 is such a simple protocol that most of the features don't
apply to a POP3-only server.

If you don't want the index files to live inside the users' home
directories, take a look at the INDEX and CONTROL keys in the mail_location
docs:

https://doc.dovecot.org/configuration_manual/mail_location/#format

While that still creates the files, you can move them off to a location that
the users do not see.

Jeff.

On Wed, 17 Jun 2020, Josef 'Jeff' Sipek wrote:
> On Tue, Jun 09, 2020 at 12:32:18 +0200, Binarus wrote:
> ...
>> ./mail/inbox
>> ./mail/.imap
>> ./mail/.imap/dovecot-uidvalidity
>> ./mail/.imap/dovecot.list.index.log
>> ./mail/.imap/dovecot-uidvalidity.5edce848
>> ./mail/.imap/INBOX
>> ./mail/.imap/INBOX/dovecot.index.log
>> ./mail/.imap/INBOX/dovecot.index
>> ./mail/.imap/INBOX/dovecot.index.log.2
>> ./mail/.imap/INBOX/dovecot.index.cache
>
> The .imap directory isn't really about IMAP.  It is sort of a generic
> directory that just happens to have "imap" in the name.  The
index files you
> see are required for various features inside dovecot to work properly. 
Many
> of them are related to performance rather than a specific protocol.
Spot on.
> If you don't want the index files to live inside the users' home
> directories, take a look at the INDEX and CONTROL keys in the mail_location
> docs:
>
> https://doc.dovecot.org/configuration_manual/mail_location/#format
>
> While that still creates the files, you can move them off to a location
that
> the users do not see.
Or you can create in-memory indices, but that is a solution to the wrong
problem.

By specifically stating in mail_location that ~user holds mailboxes,
you are telling Dovecot an untruth.  It's better to tell Dovecot user
mailboxes (other than INBOX) don't exist, rather than to push all the
indices under the carpet.

Joseph Tam <jtam.home at gmail.com>

On 17.06.2020 17:41, Josef 'Jeff' Sipek wrote:
> On Tue, Jun 09, 2020 at 12:32:18 +0200, Binarus wrote:
> ...
>> ./mail/inbox
>> ./mail/.imap
>> ./mail/.imap/dovecot-uidvalidity
>> ./mail/.imap/dovecot.list.index.log
>> ./mail/.imap/dovecot-uidvalidity.5edce848
>> ./mail/.imap/INBOX
>> ./mail/.imap/INBOX/dovecot.index.log
>> ./mail/.imap/INBOX/dovecot.index
>> ./mail/.imap/INBOX/dovecot.index.log.2
>> ./mail/.imap/INBOX/dovecot.index.cache
>>
>> While there are no .imap subdirectories in other parts of the home
>> directories any more (which was the main goal), there are still at
least
>> three unnecessary files plus one unnecessary directory with four
>> unnecessary files left. This is an ugly waste of resources, but it
won't
>> keep me from going that way.
>>
>> Obviously, dovecot is not meant to serve only POP3 any more
> 
> The .imap directory isn't really about IMAP.  It is sort of a generic
> directory that just happens to have "imap" in the name.  The
index files you
> see are required for various features inside dovecot to work properly. 
Many
> of them are related to performance rather than a specific protocol.
> Granted, POP3 is such a simple protocol that most of the features don't
> apply to a POP3-only server.
> 
> If you don't want the index files to live inside the users' home
> directories, take a look at the INDEX and CONTROL keys in the mail_location
> docs:
> 
> https://doc.dovecot.org/configuration_manual/mail_location/#format
> 
> While that still creates the files, you can move them off to a location
that
> the users do not see.
> 
> Jeff.
> 
A little bit late, but just wanted to thank you for your explanation.

By the way, that solution is playing very well in practice - no reason
to change or improve something.

Thanks again, and best regards,

Binarus