This would be useful for those who are forced to turn over passwords in court.

Maybe is not necessary to delete all data, just login to different mailbox with fake emails, which you can create by your own.

That sounds interesting. Like a button at login that says delete all data from account and prompts you for a password. That might be useful for somepeople

An alternate decryption password that when entered deletes all sent and received emails.

Like, for example a password which would regen the encryption keys so all old mail was unreadable.

Awesome idea! Aegis Secure Hard Drives support this feature and that's why I own one.

Yeah, programmable trigger passwords would be really cool. Perhaps, for technical reasons, it would have to be the account password, that would send you into an alternative mode. One mode for deleting all or certain chosen e-mails, and one mode for "safe-mode" where the e-mail UI looks identical but hides certain e-mails, contacts etc. Like another profile. Would be useful indeed.

I've wanted this email feature for years, but have never found a provider offering it.

A related feature would be to have multiple users for the same email address, so you could put a user with lower authorisation on the phone app, which can only read emails from specified senders, and have the user with full authorisation on the desktop browser.

Genius idea, considering the fact that the Gov. can send you to jail simply for refusal to "hand over" your cryptographic key(s)*.

Our dystopian future is in writing,

http://motherboard.vice.com/read/how-refusing-to-hand-over-your-passwords-can-land-you-in-jail
http://www.legislation.gov.uk/ukpga/2000/23/section/53

[*Not that I'm implying you're doing anything of questionable legality, your simply concerned, as you should be, about your privacy.]

You sir are brilliant

Absolutely Brilliant Idea!

That's a brilliant idea. I like it.

Guard against brute force attacks and interrogations by having a second mailbox password that deletes everything.