Regarding @thunderbird, that is applicable to you too. In https://support.mozilla.org/en-US/kb/openpgp-thunderbird-howto-and-faq#w_does-thunderbird-support-autocrypt it is claimed: "Thunderbird does not support the Autocrypt philosophy that encryption should be fully automatic" Well, what is the advantage of an email non-being encrypted, always that the two senders support OpenPGP (and share the public keys) or whatever common encryption method? Of course, if one does not have a public key, I understand it is impossible to make automatic encryption.
Further, I have another question: in the link above claims: 'At this time, Thunderbird doesn't support the "Gossip" feature.'
However, on the Autocrypt webpage, it appears a table where it seems thunderbird supports gossip. (https://docs.autocrypt.org/dev-status.html). Then?