Setting up a pop3 server is a very easy operation. First setup the pop3 server and then setup the accounts.
Edit /etc/services and make sure these two lines are in there and remove any # in front of them:
pop-3 110/tcp # PostOffice V.3
pop 110/tcp # PostOffice V.3
Edit /etc/inetd.conf and remove the # in front of this line:
pop-3 stream tcp nowait root /usr/sbin/tcpd ipop3d
and then restart inetd by typing:
killall -HUP inetd [Enter]Your pop3 server is now fully up and operational. Nice and simple.
It will serve mail to any user that has an account on your server using the user's login name and password. If you have users who will be using the mail server only for mail, for security reasons, you should limit their access to the other services. To make the account unusable for log in, put a * in the password field of /etc/passwd and specifying a bogus shell - like /bin/false - in the last field of the password file entry. They will still be able to get and send mail, as well as use the modem if masquerading is setup, but they will not be able to telnet, ftp, or run remote programs on the mail server itself.
Many of you might want to use imap instead of pop3. For the purposes of this article, set up pop3 first, and once everything is working, you can try imap. Although imap gives serious advantages to the user, particularly if you move between operating systems and mail clients, we have strong reservations about. Almost every time someone has attempted to crack into my server, imap was tested. There were some security concerns about earlier versions of imap which are now fixed, so we would very strongly urge you to run only the latest version if you intend to implement it on your server.