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

zhc0822

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 restartservice dovecot restart  
Reference:
 
[1] http://www.postfix.org/TUNING_README.html#conn_limit
 
[2] http://wiki.dovecot.org/MainConfig