FossaMail

FossaMail: An Open Source, Mozilla Thunderbird-based mail, news and chat client

FossaMail is an open source client for e-mail, chat and news relying on Mozilla Thunderbird. This application is practically an improved version of Mozilla Thunderbird ESR.

The main purpose when building FossaMail from source was to create a stable and fast running client. If you already have Thunderbird installations onto your computer and want to try out FossaMail, worry not. It doesn’t interfere with any other Thunderbird installation and uses its own profile folder.

Also, FossaMail supports virtually any plugin and add-on created for Thunderbird. To use it you will need a CPU that supports SSE2, enough free storage space for the installation and mail & data storage an Internet connection.