Issue Setting the default_client_limit value for dovecot by Plesk as specified by the instructions

[andreios]

When using Plesk to setup maximum number of connections, under mail server settings (in my case 1024), the client_limit setting is not adjusted as intended.
I found this support article that talks about this problem.

https://support.plesk.com/hc/en-us/articles/12377565572759--Warnings-in-var-log-maillog-on-Plesk-server-client-limit-is-lower-than-required-under-max-load

In this article it is suggested to increase default_client_limit to solve the problem.
However, the dovecot settings depend on Plesk and will disappear after an update.

I therefore suggest to let Plesk do the setting by calculating the setting as follows.
This is the warning that doveconf gives me:

doveconf: Warning: service auth { client_limit=1000 } is lower than required under max. load (2248). Counted for protocol services with service_count != 1: service managesieve-login {
process_limit=100 } + service pop3-login { process_limit=1024 } + service imap-urlauth-login { process_limit=100 } + service imap-login { process_limit=1024 }
doveconf: Warning: service anvil { client_limit=1000 } is lower than required under max. load (2251). Counted with: service managesieve-login { process_limit=100 } + service pop3-login { process_limit=1024 } + service imap-urlauth-login { process_limit=100 } + service imap-login { process_limit=1024 } + service auth { process_limit=1 }

This shows exactly how the value is calculated. If I insert the larger of the two calculated values into dovecot.conf, the message disappears.

default_client_limit = 2251

Here are the dovecot directions for "anvil" and "auth" in the docs.

Service configuration — Dovecot documentation

Service configuration — Dovecot documentation

 

[Peter Debik]

That is strange as the files in /etc/dovecot/conf.d should not be overwritten on updates.

 

[andreios]

All files in my /etc/dovecot/*/* have this banner

# PLEASE DON'T EDIT ANYTHING IN THIS FILE! ANY CHANGES WILL BE LOST ON UPGRADE.

or this

#DO NOT MODIFY THIS FILE BECAUSE IT WAS GENERATED AUTOMATICALLY,
#SO ALL YOUR CHANGES WILL BE LOST THE NEXT TIME THE FILE IS GENERATED.

Only exception:
11-plesk-security-ssl.conf and *.pem

The files that are manged by setting max connections on the Plesk GUI are

conf.d/92-plesk-service-imap.conf
conf.d/92-plesk-service-imap-login.conf
conf.d/92-plesk-service-pop.conf
conf.d/92-plesk-service-pop-login.conf

Anyway I guess in this issue it would be best practice to let Plesk manage default_client_limit, as it seems to manage everything in dovecot one way or another. .

 

[Peter Debik]

I must admit that I've been ignoring this and put my own config into the files anyway. The only situation where this ever needed a manual intervention was on the centos2alma upgrade when Dovecot was completely reinstalled. But many years before the configs were never changed.