When you check your e-mail, the e-mail program connects to your mail server to see if there are any new messages in your mail directory. If its configured to used the Post Office Protocol (POP3), it downloads the messages locally and deletes them from the server. If it's configured to use Internet Message Access Protocol (IMAP), the mail remains on the server and you manage it remotely.

Dovecot handles both protocols out of the box. Since we've already installed Dovecot for its SASL functionality, we could just open the standard ports for POP3 and IMAP traffic in the system's firewall and be done. However, the connections would be unencrypted and information would be transmitted across the network in plain text. This recipe teaches you how to secure these connections with SSL.