Install courier-imap by entering the following commands in the terminal:
sudo apt update sudo apt install courier-imap
Description:
Courier mail server - IMAP server
The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP, TLS, and HTTP. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list services within a single, consistent, framework. . This package provides an IMAP server that accesses email stored in Maildirs format mailboxes. This server has an extremely small footprint and provides shared and virtual shared folders. . IMAP over TLS is handled by the regular IMAP daemon in conjunction with the TLS wrapper.
Homepage: http://www.courier-mta.org/
Version: 4.18.1+0.78.0-2ubuntu2
Section: universe/mail