Re:FastMail loses customers, faces calls to move over anti-e...
by askmike on Wednesday February 27, 2019 @02:58AM
(#19261702)
The difference is that Enigmail is maintained by an open source community, Thunderbird by Mozilla. Also the protocol your mail client uses to talk with your email server (POP or IMAP) don't really support the flexibility to send the keys over easily. As opposed to your clientside Protonmail client managed by javascript that can AJAX the keys to the mothership.
That's the risk. By default, the filesystem isn't accessible to Javascript. But here, you've authorized key access for encryption and decryption. I suppose that Thunderbird and Enigmail could be modified to do much the same. But arguably that would be discovered quickly.