Definitely a cool idea. Though I feel like I would want to be able to have more flexible rules than "folder" to decide what the account can access. For example,

Definitely a cool idea. Though I feel like I would want to be able to have more flexible rules than "folder" to decide what the account can access. For example, "all unread emails newer than 1 day and containing the string 'registration'" would be quite useful. To be fair, it would be a bit of a pain to implement but it might be useful for the usecase of wanting to just get a single email. It's also quite annoying that you have to set up the keys beforehand. Though, obviously if you could connect to the server to create keys then you wouldn't need to use this. :/