For example: You have two mail accounts on two mail servers. You want to implement webmail on your workstation to read all these mails in your browser. Then use fetchmail on your workstation, it can retrieve your POP3 email from both your mail accounts.
Tell fetchmail to get your mail from yourmailserver.de to your desktop:
Now you can use your desktop as mail server using mutt.
Configure your Fetchmail
In your home folder, find .fetchmailrc. An example configuration is:
poll mail.myServer.de user "myName" pass "myPassWord" mda '/usr/bin/procmail -f fetchmail'
Everytime you start fetchmail from now, your mail gets fetched from mail.myServer.de, for name "myName" with password "myPassWord".