imap connections limted to 10 makes clients fail to connect

[chymian]

After I moved my mail-server to cloudron, I experienced regular erros on my thunderbird, saying the server rejected my login.
It was not updating the IMAP-folders and the only way to read my emails, was through K-9.
in a quiet moment, I installed KDEPIM and Kontact provided me with a more helpful err-msg.

in German:

Anmeldung fehlgeschlagen, die Serverantwort lautet:
A000002 NO Maximum number of connections from user+IP exeeded (mail_max_userip_connections=10) [ UNAVAILABLE ]

I do have 2 accounts configured in my mail-client, with a lot of IMAP-folders and never experienced a pbl. with other mail-servers I used so far.

ClientSystem: Debian buster,
KDE 5.54
thunderbird: 60.5.1-1
kdepim: 4:17.12.3+5.102
kontact: 4:18.08.3-1

[girish]

@chymian It seems it's hitting the rate limit. Can you try this:

docker exec -ti mail /bin/bash

edit /run/dovecot/dovecot.conf. add something like this:

protocol imap {
  mail_max_userip_connections = 50
}

Then (inside the container)

supervisorctl restart dovecot

Note that the above setting will not persist server reboot. If the above works, we can get it fixed in the coming update.

[chymian]

from a quick test, it seems to work with a limit set to 50
TB works, even with sieve editor open.
if I don't report otherwise within a week, it is a working solution.

thx johannes
guenter

[girish]

OK, I have fixed the code as well, so it will part of next update (3.6). Until then please update file.