-;; It also begins to implement the IMAP Threading extension RFC. The
-;; implementation lacks the reference and subject canonicalization of
-;; the RFC.
+;; It also begins to implement the threading section of the IMAP -
+;; SORT and THREAD Extensions RFC at:
+;; http://tools.ietf.org/html/rfc5256
+;; The implementation lacks the reference and subject canonicalization
+;; of the RFC.