16.2.2 About POP and IMAP

The Post Office Protocol (POP) is an email access protocol that email client applications use to retrieve email messages from the mailbox on a remote server, typically maintained by an Internet Service Provider (ISP). POP email clients usually delete the message on the server when it has been successfully retrieved or within a short time period thereafter.

The Internet Message Access Protocol (IMAP) is an email access protocol that email client applications use to retrieve email messages from a remote server, typically maintained by their organization. The entire message is downloaded only when you open it, and you can delete messages from the server without first downloading them. Email is retained on the server when using IMAP.

Both POP and IMAP allow you to manage mail folders and create multiple mail directories to organize and store email.

The dovecot package provides the dovecot service that implements both an IMAP server and a POP server.

By default, the dovecot service runs IMAP and POP together with their secure versions that use Secure Socket Layer (SSL) encryption for client authentication and data transfer sessions. The IMAP and POP servers provided by dovecot are configured to work as installed. It is usually unnecessary to modify the configuration file, /etc/dovecot.conf.

For more information, see the dovecot(1) manual page and /usr/share/doc/dovecot-version.