I recently learned of this: https://addons.mozilla.org/en-US/thunderbird/addon/paranoia/ https://github.com/gjedeer/paranoia It parses email headers, looking for Received: line info that reflects encryption, and displays a graduated happy/sad face based on how many exchanges appear to have been encrypted. The face can be clicked on for summary info. I think there are some issues... - Systems which use encryption but don't insert the header information - Detection logic appears to need improvement - Reporting could be improved to surface more info where available (ciphersuite, verify, ...) - Received lines are inserted by receiving systems and thus encryption information for sent messages can't be bubbled up to the user via this approach (remember that). - Server certificates often aren't verified and self-signed certificates are pretty common, so you have to factor that in. - Emails can be compromised via the server(s) rather than the connection between servers too. I do like the idea of email clients surfacing more info though! Such projects would seem to have potential.