From the Changelog:
The keys used are:
!: modified feature, -: deleted feature, +: new feature
1.8.0 (2017-02-24):
- $locale has been removed. Mutt now respects the LC_TIME setting
instead. See also $attribution_locale.
+ $attribution_locale can be used to override the date formatting in
attribution strings. When unset, Mutt will use the locale
environment, but note the default value of $date_format has a
leading '!' which says to use the C-locale.
! Message-id and mail-followup-to headers are now preserved for recalled
messages.
+ <unsidebar_whitelist> added to complement <sidebar_whitelist>.
! The pager position is reset to the top when toggling header-weed.
! IMAP messages moved to $trash via server-side copy are marked as read.
+ <root-message> jumps to the root message of a thread.
! Piped text attachments are charset converted.
+ Added %F to $attach_format, to show the content-disposition filename.
%d will fall back to %F which will fall back to %f.
+ <rename-attachment> allows an attachment name to be changed, without
modifying the underlying file's name.
! Mutt will look for the user's muttrc additionally in
$XDG_CONFIG_HOME/mutt/.
+ Compressed mbox and mmdf files are now supported via open-hook,
close-hook, and append-hook. See contrib/sample.muttrc-compress
for suggested settings. Note this is a compile-time option:
--enable-compressed.
+ When $flag_safe is set, flagged messages cannot be deleted.
+ The '@' pattern modifier can be used to limit matches to known aliases.
+ <mark-message> creates a hotkey binding to a specific message. The hotkey
prefix is specified via $mark_macro_prefix.
+ <setenv> and <unsetenv> can be used to add/remove environment variables
passed to children.
! Mutt will now use the built-in OpenSSL SSL_set_verify() callback
to verify certificates. This allows better support for verifying
chains, including alternative chain support.
+ $uncollapse_new controls whether a thread will be uncollapsed when a new
message arrives.
! $to_chars and $status_chars now accept multibyte characters.
+ <subjectrx> allows replacing matching subjects with something else.
This can be used to declutter subject lines in the index.
+ <edit-label> can be used to add, change, or delete a message's X-Label.
! Pattern expressions with ~y support label tab completion.
+ The header cache now also supports Kyoto Cabinet and LMDB as
backend databases.
Astroid was unable to run in a pure environment because it couldn't find
the necessary icons. This fixes that issue, and was tested with
`nix-shell --pure`