+Foreign Messages
+****************
+
+Messages MAY be imported from other networks and systems which have no
+knowledge of salmon signatures. The salmon signature in this case MUST be the
+exact string 'NOTSIGNED' to indicate that the author (From address) cannot be
+validated using salmon verification. This message MUST be relayed by a Sender
+who can provide a valid salmon signature of the message. Delivery systems MAY
+reject foreign messages.
+
+