Yes, I'm about to kill off another project Innuendo 
FossaMail is a Windows/Linux x86/x64 mail/news/chat client based on Thunderbird but using the optimised Pale Moon browser core.
FossaMail:
System requirements:

FossaMail is a Windows/Linux x86/x64 mail/news/chat client based on Thunderbird but using the optimised Pale Moon browser core.
FossaMail:
- Is built from source with compiler optimizations geared towards an as stable and smooth operation of the client as possible (Pale Moon-alike optimizations).
- Uses the Pale Moon browser core as its back-end. The client is therefore based on Pale Moon rather than other Mozilla-powered products.
- Uses its own profile folder on your system. This means it will not interfere with existing Thunderbird installations.
- The default profile location is %APPDATA%\FossaMail
- Should be compatible with all Thunderbird (v24/25b era) add-ons and plugins.
- Is available in 32-bit (x86) and 64-bit (x64) versions for both Windows and Linux.
- Comes with an optional calendar/organizer add-on (Lightning, available from the download location below) that will allow it to be used in a Microsoft Outlook style information manager fashion.
System requirements:
- Operating system either:
- Windows Vista or above (Windows XP is not supported), OR
- A recent Linux distribution (it will not run on particularly old kernel/libc combinations)
- A processor with SSE2 support
- Sufficient hard drive space to install and store your e-mail and other data
- An internet connection ;-)



