TorBirdy - IMAP issue
Part of discussion on tor-dev mail list.
Accessing an email server via IMAP may leak data by saving a draft on the remote server.
While writing a message on Thunderbird, it is automatically saved as a draft, which by default is sent to the IMAP server. So the server will be able to read that message.
That's a big problem when the message should be encrypted before sent. So the email provider will be able to read sensitive data on those drafts in cleartext and the user probably won't notice.
To solve this the user need to manually set the account drafts settings (in Copies & Folders) to keep drafts on Local Folders.
I think Torbirdy should do it by default.
This info should be added to known issues on Torbirdy wiki.
I know Torbirdy developers recommend POP over IMAP, but as a mailtor.net user I don't have any other option.
I've checked it again. Write, wait it to be saved, close and open your email via web-mail. And thats my draft in cleartext on mailtor.net server:
Icedove 17.0.10 Enigmail 1.6 TorBirdy 0.1.2
It doesn't have anything to do with TorBirdy.
I did not say it is TorBirdy fault.
But yes it has everything to do with TorBirdy. It is an anonymity and security tool and tries avoid leaks. Maybe you just don't see it as a leak.
Anyway the users must know it may happen.
All you really have to do, is to have Encryption on by default in Enigmail. Your drafts are now going to be encrypted. Problem solved!
By default, Enigmail saves an encrypted copy of the message. This is the default setting  and I think it also confirms this when it saves an encrypted message for the first time. TorBirdy does not modify this setting so it should be enabled by default for Enigmail.
Enigmail asks to save an encrypted draft only when you enable encryption to that message. If you forget to set the encryption and write it will be saved in cleartext without asking anything.
When you are sending the email Enigmail asks if you really wanna send unencrypted, but the draft already have been sent unencrypted on the IMAP server.
Enigmail should ask always when saving a draft remotely. Even locally it should.
And TorBirdy should help prevent this to happen.
Now Thunderbird is set to not automatically create/save drafts. Works like a charm. =)
That should be default set by both Enigmail and TorBirdy. Also should set to save locally, instead of remotely, if the user wants to save a draft.