JWZ's algorithm: <https://www.jwz.org/doc/threading.html>.
This holds a $smsg and is only used for message threading.
This wrapper class may go away in the future and handled
JWZ's algorithm: <https://www.jwz.org/doc/threading.html>.
This holds a $smsg and is only used for message threading.
This wrapper class may go away in the future and handled