Am I the only one thinking that the issue comes from the fact that DKIM stuff is (I assume) inserted into the email's headers? DKIM is used for transfer of email, to make sure that the originating server is who it pretends to be. Shouldn't that be part of an envelope of the email, which would be discarded once the email has been received and its sending server verified and authenticated? Like for paper mail, one does _usually_ not keep the envelope (though I admit that there may be exceptional situations where it may be preferable to keep the envelope).

-- In the interest of users (will most probably never happen), all incoming emails should be ignored and dismissed unless the recipient has explicitly specified that it accepts email sent from a given email address. Wouldn't this give the power back to the users?