#792 Autocrypt messages are unreadable on Thunderbird without Enigmail

[Tristan Miller]

If you use Thunderbird+Enigmail to send a signed message with an autocrypt header, that message will be unreadable if the recipient has Thunderbird but not Enigmail. This is because Thunderbird attempts to display the entire autocrypt header, which takes up all remaining space in the message window (or pane), leaving no room for the message contents. See the attached screenshot.

I'm not sure if this is a problem with Thunderbird itself or Enigmail or both.

[Patrick Brunschwig]

This only happens if the recipient once installed Enigmail 2.0, and then uninstalled it again.

It happens because Enigmail on TB 52 needs to use a workaround to access the Autocrypt header. On TB 60, there is better solution for this.

If you disable/uninstall Enigmail, you need to manually reset the option mailnews.headers.extraExpandedHeaders to make the header go away. To do this, go to the Thunderbird Preferences > Advanced Tab > Config Editor and search for
mailnews.headers.extraExpandedHeaders

[Tristan Miller]

OK. This also makes it difficult to view messages when Thunderbird is started in safe mode. If TB 60 solves the problem then that's good enough for me (since running in safe mode or uninstalling Enigmail are fairly rare occurrences).

[Patrick Brunschwig]

I added a function in Enigmail that resets the preference if Enigmail is disabled or uninstalled, or if Thunderbird is shut down (but not if TB crashes).