This could also be set as a rule. Delete what is set. if you login with this password -
Delete, alle mails in this folder, mails labeled this and this and then empty trash.

when entering an alternative secret password, delete the entire mailbox permanently

Very nice idea.

I think the simpler idea here is the dummy inbox.
Excellent idea, along the same line, can a sent email expire one hour after its read...or maybe 24hrs?

Shut up and take my money.

Or create a third password that would open up a fake mailbox with fake emails :)

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.

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.

You sir are brilliant