Setup mail server (postfix, dovecot, mysql) test pop3 error

I have setup mail server by following this link http://library.linode.com/email/postfix … 0.04-lucid">http://library.linode.com/email/postfix/dovecot-mysql-ubuntu-10.04-lucid

at the step

You can test your POP3 server to make sure it's running properly by issuing the following command.

telnet localhost pop3

I get problem

Trying 127.0.0.1…

telnet: Unable to connect to remote host: Connection refused