Courier is a completely free, cross-platform and open source mail transfer agent (MTA), an integrated mail and groupware server based on open protocols, such as IMAP (Internet Message Access Protocol), POP3 (Post Office Protocol 3), SSL (Secure Sockets Layer), LDAP (Lightweight Directory Access Protocol), ESMTP, and HTTP.
Provides webmail and mailing list services
It is a mature and powerful software that provides webmail and mailing list services within a single and consistent framework, using the ESMTP (Extended SMTP), IMAP and POP3 protocols.
The best thing about Courier is that its mail filtering engine, the IMAP server, and the webmail server are available as separate packages, and can be easily installed and integrated with other mail server applications.
Getting started with Courier
Installing the Courier software on a GNU/Linux operating system is quite easy, as all you have to do is to download the latest release from Softpedia, saving the archive on your Home directory. Unpack the archive, open a Terminal app, and move to the location where you’ve extracted the archive file (e.g. cd /home/softpedia/courier-0.74.1).
Then, run the ‘./configure && make’ command to configure and compile the program. After a successful compilation process, run the ‘sudo make install’ command to install Courier system wide.
During the installation, you will be ascked to create directories for the web-based administration tool, as well as to create a SSL certificate. Several configuration files are available in the /etc/courier folder.
Under the hood
Taking a quick look under the hood of the Courier project, we can notice that the C++, C and Perl programming langauges have been used to write its source code. Courier is compatible with both 32 and 64-bit computer platforms, it presents itself as a non-interactive daemon, and can be deployed on any GNU/Linux or BSD machine.