[Dovecot] Slow connections with POP3 service

[V S Rao]

Hi All, 

I am facing a very strange issue with the pop3 server for the past one week. 

I run my mail service using sendmail & use UW-IMAP for POP3 & IMAP service. We have around 5000 users. 
Suddenly for the past one week I am facing very slow connections for POP3 alone on that server. Other services such as SMTP, IMAP, telnet, ssh etc work fine. 

Assuming that UW-IMAP may have an issue, I download the latest dovecot, compiled it and installed it. This also gives the same issue. 

I do not any firewall issues nor iptables is enabled. I have checked on the network to ensure that I do not have any kind of virus or DoS attacks using an IDS. I am unable to see any 'Strange' messages in /var/log/messages or maillog. What is strange is that it works one day without any issues and the next day the problem persists. 

Even a telnet to localhost on port 110 is very very slow. 

Can someone help with any ideas on how to troubleshoot? This is our production box. 

Thanks 
V S Rao