+mail, pruned from all but self sigs and sigs done by you. The mailed
+key is encrypted with itself as a means to verify that key belongs to
+the recipient.
+
+Since we do not upload the new signatures, or import them into our
+main keyring, the signature only gets public if:
+ - the email address is valid, and
+ - the person reading the email can decrypt the mail (if it was sent
+ encrypted).
+Therefore we achieve the same level of security as common Challenge
+Response systems like CABot, without all the extra hassle of those
+systems.
+
+FEATURES
+--------