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

[Binarus]

On 07.06.2020 17:56, Hendrik Boom wrote:
> On Sun, Jun 07, 2020 at 08:44:51AM +0200, Binarus wrote:
>> Dear all,
>>
>> on our mail server, I let sendmail deliver incoming messages to a file in mbox format called "inbox" in each user's home directory.  Now I would like to use dovecot as POP3 server so that users can let their MUA download their messages via POP3. I do not want to use any IMAP functionality.
>>
>> The POP3 part works with the configuration shown below, but nevertheless there is a problem which is a show stopper:
>>
>> Although I think I have turned off IMAP (e.g. no IMAP listener), dovecot still creates .imap directories and does so in a very weird way. It creates one .imap subdirectory in every subdirectory of each user's home directory, and for every file in each user's home directory creates an additional subdirectory with the same name in its .imap directories. It does this recursively, and 1000 files in a user's home directory would mean 1000 additional subdirectories.
>>
>> Of course, I can't live with that. I know that the dovecot documentation discourages using the home directory as mail location, but in my case this should not be a problem at all if IMAP is not used. I have played around with dovecot for several days, but could not solve that problem.
>>
>> So how can I turn off IMAP completely and prevent dovecot from creating any .imap directories or IMAP related files?
> 
> I suppose you'd be OK with having IMAP but having it look *only* at the 
> designated mbox file.
> 
> That would be something I could use.

Thank you very much for your comment. You are completely right - I could very well live with that solution.

However, I have researched for many hours before posting here, but I could not find out how to achieve this. As I have described in my first post, dovecot created an .imap subdirectory in each directory which existed, and created one subdirectory (within the .imap directory) for each file which existed, and it did so recursively. Whatever portions in the configuration files I commented out, and whatever service I disabled by other means (e.g. by giving Port = 0), I could not prevent dovecot from messing up users' home directories completely, i.e. I could not make it use only the mbox file and leave the directories as-is otherwise (possibly adding a file or two for management and housekeeping).

This is extremely weird and not acceptable; imagine 10,000 directories being created for nothing solely because there are 10,000 files. Plus, it is a behaviour which previous versions did not show (I have pulled over the configuration from another system running Debian jessie, where the problem did not arise). I still can't understand why it does IMAP things at all, given that I have protocols = " pop3".

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?

Thank you very much again,

Binarus