threads list

thread sorting in threads list
try to support maildir folders?
- allow moving
- auto move a thread in the same folder?
better default column sizes
context menu
tags as tree instead of list
- folding stored in ui preferences

mail view

collapse quoting in message view
save/view attachments
xdg thumbnail for attachments?
better tags display/edit

sync

refresh views when notmuch has been run
fetching progress info

composing mail

forward mail
add attachments
save to drafts
resume draft
asynchronous sending

mail operations

delete message
delete thread

encryption

encrypt/sign mails
decrypt mails
(support autocrypt?)
saved searches
autocomplete tags

configuration

scriptability/plugins
prefs dialog
propose default notmuch plugins for auto-tagging all messages in a thread, etc.
ui plugins
have always-loaded plugins like ui plugins?
list view for conf stackedwidget
be more resistant to config errors

extra-mail interactions

support JSON-LD for quick mail actions
look for external address book interaction
- and suggest frequently used together addresses
look for external calendar interaction

spam control

mark spam/ham
- done by filter plugins?

help

first-run wizard
supports creating a notmuch db
autodetect exising mbsync/msmtp/etc. configs and propose to auto-load plugins for them

speed

solve locks and UI locks when editing tags etc.