3rd party key signing
Public Key servers can be compromised, keys can be modified etc.
I would love a feature that would allow for 3rd party key-signing, or key-signing via other ProtonMail account holders.
Rev. LeRoy Cressy commented
I've been using various versions of PGP since 1995 and I would love for ProtonMail to enable key signing by utilities like GnuPG, PGP, enigmail, or whatever. The public keys could then be posted on a key server and ProtonMail could sync their key server with all of the other key servers.