Warnings in /var/log/maillog on Plesk server: client_limit is lower than required under max. load

Renan Poss Moreira

Updated January 13, 2026 19:09

Plesk for Linux kb: technical ABT: Group A

Applicable to:

These warnings can be seen in /var/log/maillogor /var/log/messages:
CONFIG_TEXT: dovecot: config: Warning: service auth { client_limit=1000 } is lower than required under max. load (1396)
dovecot: config: Warning: service anvil { client_limit=1000 } is lower than required under max. load (1399)
Roundcube shows 500 Internal Server Error with the following errors in /var/log/httpd/error_log file:

CONFIG_TEXT: [fcgid:warn] [pid 12406:tid 140260554016512] [client 203.0.113.2:42198] mod_fcgid: read data timeout in 45 seconds, referer: http://webmail.example.com/
[core:error] [pid 12406:tid 140260554016512] [client 203.0.113.2:42198] End of script output before headers: index.php, referer: http://webmail.example.com/
Mail clients might fail to connect.

The default_client_limit parameter is too low for Dovecot.

Connect to the server via SSH
Note: If direct SSH access to the server is not possible, contact server administrator for further assistance.
Create /etc/dovecot/conf.d/10-master.conf file using text editor to change client_limit for all dovecot services:
CONFIG_TEXT: default_client_limit = 1500
Restart dovecot to apply the changes:

# service dovecot restart

Note: If after raising the default_client_limit the same error message still showing up, increase more the limit.

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