Avoid Lots of POP3-Login or IMAP Processes by Configurating Postfix and Dovecot

My VPS has hundreds of POP3-Login and IMAP processes recently. Even each process consumes only 0.1% of the main memory, 100 processes can eat up 10%!

 

After seeking help to Google, I' ve found the answer:

 

First , set max connection number of smtp process.

 

1. Edit Postfix configuration file. If you installed Postfix by yum, the configuration file should be located at /etc/postfix/main.cf;

 

2. Add the line below at the bottom of main.cf

smtpd_client_connection_rate_limit = 100

 Tuning the number as you like.

 

Second , modify the configuration of Dovecot.

 

1. Edit Dovecot config file. If you installed it by yum, this file should be located at /etc/dovecot.conf

 

2. Add the line below

login_max_processes_count = 20

 If the processes number exceeds 20, older ones will be destroyed.

 

Third, restart services.

 

service postfix restart
service dovecot restart

 

 

Reference:

 

[1] http://www.postfix.org/TUNING_README.html#conn_limit

 

[2] http://wiki.dovecot.org/MainConfig