We chose Courier IMAP as our mail access agent (MAA) because it is easy to configure and maintain. It supports the IMAP4 and POP3 protocols, allowing mail user agents (MUAs) to get their email from the mail server. As the name suggests, IMAP is the primary protocol. IMAP has many advantages over POP; chief among them is support for folders, and keeping the emails on the server.

We (Jeff Muse and Craig Buchek mainly) chose Courier IMAP, as it's much easier to configure and maintain than Cyrus. Plus, there's good documentation on setting it up to work with Postfix at http://workaround.org/articles/ispmail-sarge and other sites.

(See this article for a description of all the pieces involved in email delivery.)

We need to install several pieces of the Courier email system. First, some pre-requisites:

apt-get install libfam0c102 courier-base courier-ssl courier-authdaemon

When asked if you want to use configuration directories, answer Yes.

Install the IMAP pieces, and the POP pieces:

apt-get install courier-imap courier-imap-ssl
apt-get install courier-pop courier-pop-ssl

Install the recommended packages and documentation:

apt-get install courier-doc

Don't forget to create /etc/courier/pop3d.pem and /etc/courier/imapd.pem SSL certificates.

cp /usr/lib/courier/*.pem /etc/courier/

NOTE: I'm not sure this is correct, or if we should create certificates with openssl.

TODO.

TODO.

TODO.

• Document configuration details. Certificates were made using the ssl-cert packages make-ssl-cert script. We had to edit the /usr/sbin/make-ssl-cert script and add the -days 3650 to the openssl command that actually creates the certificate, otherwise it defaults to 30 days (have not yet figured this one out).
• Make sure IMAP isn't filling up the log files again.

• BINC IMAP - looks simple yet robust; recommended by Matthew Porter
• Dovecot - new, but in active development; concentrates on security, simplicity, speed, low memory use
• UW-IMAP - the original Open Source implementation
• Cyrus IMAP