A simple and fast e-mail client from Calypso. It offers the ability to support multiple email accounts, interface configuration, automatic archiving functions, built-in anti-spam filter, the ability to switch the HTML view to plain text at the touch of a button and many other functions. A distinguishing feature of Courier is the ability to mark the titles of individual messages with different font and background colours (Color Markers function), so you can easily find different types of messages.

The advantage is also small system requirements and saving all messages and program settings in one .box file (which guarantees trouble-free data transfer, e.g. after reinstallation of the system). Unfortunately, Courier does not have a Polish interface and has not been developed for some time.

As part of a time-limited offer, the manufacturer offers the possibility to register the program completely free of charge. Details can be found on the program page.