Claws Mail 64bit, running on Windows 8.1 64 bit, crashes immediately when composing a message and either (1) characters count reaches 50 or whatever number is set in global config for autosave or (2) when saving the draft on purpose (Ctrl+S or via menu). Happens the same if upgraded over 3.15.x or clean fresh install.
I confirm crashes with the experimental 64bit build. (32 bit build is working fine)
*** This bug has been marked as a duplicate of bug 3957 ***