I'm looking for a set of emails encrypted (and signed) by a variety of email clients in order to test a mail client. A downloadable mbox file along with test gpg keys would be ideal for this.
There seem to be a variety of ways that emails are encrypted (and signed), so getting all of them to work is difficult. And then you find another client that gets it wrong in a slightly different way, and you want to refactor your code but not break decryption of any emails you already support.
So does anyone know of such a dataset? Or failing that, a good list of the ways that different bits of software encrypt emails?