dovecot limitations

if you are faced with process limitation


Unfortunately, we could face with defaults dovecot processes limitations and got warning in the

$ less /var/log/maillog | grep "Warning"


Feb 7 14:32:10 mail dovecot: master: Warning: Sent SIGKILL to 128 imap-login processes
Feb 7 14:32:10 mail dovecot: master: Warning: service(imap-login): process_limit (128) reached, client connections are being dropped
Feb 7 14:32:12 mail dovecot: master: Warning: Sent SIGKILL to 127 imap-login processes
Feb 7 14:32:14 mail dovecot: master: Warning: Sent SIGKILL to 128 imap-login processes


In the number of mail servers, the config file could be named in different ways, so we can find parameter witch should edit with grep:


$ grep 128 /etc/dovecot/conf.d/*.* ... /etc/dovecot/conf.d/exim-dovecot-mysql_config.conf:process_limit = 128


Now, let’s open this config file and find out certain parameter:


$ nano /etc/dovecot/conf.d/exim-dovecot-mysql_config.conf
Ctrl-W -> type 128 -> Enter
"
service imap-login {
chroot =
# client_limit = 256
client_limit = 512
#process_limit = 128
process_limit = 256
process_min_avail = 3
service_count = 1
vsz_limit = 64 M
}


As you can see in the previous code sample it was commented old values and added new values 2 times more. So, it is up to you how much limit you need to have.


After saving edited file we need to restart dovecot service and check the actual configuration of it


$ systemctl restart dovecot
$ systemctl status dovecot
$ dovecot -n | grep process_limit process_limit = 256

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