is disqualified from being journaled, perhaps because
it is itself a journalized message and we wish to
avoid double journaling.
+K Reply-To the Reply-To header for mailinglist outbound messages
L List-ID Mailing list identification, as per RFC 2919
M Message Text Normal ASCII, newlines seperated by CR's or LF's,
null terminated as always.
W Wefewences Previous message ID's for conversation threading. When
converting from RFC822 we use References: if present, or
In-Reply-To: otherwise.
+ (Who in extnotify spool messages which don't need to know
+ other message ids)
Y carbon copY Optional, and only in Mail messages.
0 Error This field is typically never found in a message on
disk or in transit. Message scanning modules are