I am giving Delta Chat a try, for chatting over (optionally GPG-encrypted) email. I cannot yet attest to how well it works, join me in trying!
Email address: delta.one@6d617274696a6e.696e626f78.com.
GPG key: AB4E A120 390E FD23 9A51 B3C7 1804 2A31 5F1C 0A0C.
This QR code may let you verify my key, by enabling the option Settings → Advanced → Labs: QR code options:
Security note: I am not sure how this validation functions exactly, as I believe you need to recieve a message from me first before you gain my key. Neither do I know how Delta Chat will handle my key expiring on the 1st of 2019.