Hello Clément,

Clément Lassieur <clement@lassieur.org> writes:

[…]

>>>>> Sometimes the Dovecot service stops working, which is difficult to
>>>>> notice.
>>>>
>>>> When it “stops working”, does the Shepherd service go down?  Does “herd
>>>> status dovecot” shows that it was respawned?  Is the dovecot process
>>>> still around?
>>>
>>> The dovecot process is still around, yes.  I has happened several times
>>> already (maybe 5), 

Do you mean the warning you posted before?
--8<---------------cut here---------------start------------->8---
Sep 4 11:47:12 mail2 dovecot: master: Warning: service(imap-login): process_limit (100) reached, client connections are being dropped
--8<---------------cut here---------------end--------------->8---

The ‘dovecot-configuration’ record has a ‘default-process-limit’ which
is setted to 100 by default.  Could you try to increase it?

Also a ‘process_limit’ configuration string is described on Dovecot Wiki.

  https://wiki.dovecot.org/LoginProcess

Thanks,
Oleg.