Aggressive LMTP header cleanup

This will remove all headers possible during LMTP delivery.

From header: required or clients do not process the message correctly

Message-Id header: required for clients to know which messages have been
downloaded

cmdeploy/src/cmdeploy/postfix/lmtp_header_cleanup

@@ -1,2 +1,3 @@
-/^DKIM-Signature:/            IGNORE
-/^Authentication-Results:/            IGNORE
+/^From:/            DUNNO
+/^Message-Id:/      DUNNO
+/.*/                IGNORE