My columns
For each thread, show only
- the number of unread/read messages
- a star if unread messages exist
- the subject.
(with-eval-after-load 'notmuch
(setq notmuch-search-result-format
'(("count" . "%9s ")
((lambda (_ thread)
(concat
(propertize
(if (member "unread" (plist-get thread :tags))
"*" " ")
'face
'notmuch-tag-face)
" ")))
("subject" . "%s"))))