Mozilla Thunderbird is a free and open-source cross-platform email client, personal information manager, news client, RSS and chat client developed by the Mozilla Foundation. The project strategy was originally modeled after that of Mozilla’s Firefox web browser.
Thunderbird promotes services like gmail and the like for ease of setup. These are trade-based. So for that I will give it just 3 blocks.
Thunderbird is a great example of a trade-free service. It is a feature rich application, without asking anything from you. No data, no attention (because there are no ads), money or anything else. 5/5 blocks for this awesome application.