We actually implemented verification schemes similar to this for account holders at rsync.net. One example: - Destructive actions to an rsync.net account (man

We actually implemented verification schemes similar to this for account holders at rsync.net. One example: - Destructive actions to an rsync.net account (manual deletions, account cancellation, etc.) have an "email age" flag. If someone is requesting something dangerous from a just changed email, support looks very closely at the request and sends a heads-up to both the old and new email addresses. We also have some relief mechanisms for the occasions people get locked out of their lives by (google, et. al) - if a user can prove control over an rsync.net account by `touch`-ing filename of random hash we provide, we can start a reclamation process based on proving the ability to destroy the account anyway.