Things to add to the release notes for the next full release:

------------
NEW FEATURES
------------

- The default editor has been changed from 'vi' to 'prompter', to align with
  historical practice and reduce packaging dependencies on external programs.
- A new -checkbase64 switch to mhfixmsg(1).
- inc(1)/msgchk(1) now support STARTTLS for the POP protocol.

-----------------
OBSOLETE FEATURES
-----------------

- The MIME content cache functionality has been mostly non-functional since
  the development on nmh, and consequently all of the content caching code
  and related switches (-cache/-rcache/-wcache) have been removed.
- Support for generating and reassembling message/partial messags has been
  removed; it seems that this has been broken since 1.5 and there is very
  little support across MUAs.

-------------------
DEPRECATED FEATURES
-------------------

- The generation and verification of Content-MD5 headers is no longer
  performed.  The -check and -nocheck switches to various nmh programs
  that would control this functionality still exist, but are non-functional
  and will be removed in the next release.

---------
BUG FIXES
---------

- An -attendee switch has been added to mhical(1), for use when more than one
  (or zero) attendees match a user's mailbox.