How do I encrypt emails using Apple Mail? Gnu PGP was integrated into Mail using this project, but it appears to be dead (only supports old versions of OSX) http://www.sente.ch/software/GPGMail/English.lproj/GPGMail.html

Is there any other way to do it? Or do I have to use Enigmail for Thunderbird?
It appears this is what I was looking for: https://gpgtools.org/