remember encrypted subject for next time #2766
Description
When user receives a message from Thunderbird+enigmail, or other similar software, with encrypted subject, currently it will show "..." in inbox as a subject.
When user opens it, they will see the encrypted subject.
It may be interesting to store the subjects locally as metadata, and try to render the subjects right away in inbox, so that user knows which message to click on in the first place.
It may be even more interesting to proactively decrypt them the first time they are encountered just to show the subject, but that may be too complicated.