Mozilla Thunderbird
Mozilla Thunderbird is a free and open-source personal information manager primarily used as an e-mail client with a calendar and contactbook, as well as an RSS feed reader, chat client (IRC/XMPP/Matrix), and news client. Operated by MZLA Technologies Corporation, a subsidiary of the Mozilla Foundation, Thunderbird is an independent, community-driven project that is managed and overseen by the Thunderbird Council, which is elected by the Thunderbird community.