+This variable is overridden by buffer-local versions in message
+buffers where tag changes should be triggered when sending off
+the message. Each item in this list is a list of strings, where
+the first is a notmuch query and the rest are the tag changes to
+be applied to the matching messages.")
+
+(defun notmuch-message-apply-queued-tag-changes ()
+ ;; Apply the tag changes queued in the buffer-local variable notmuch-message-queued-tag-changes.
+ (dolist (query-and-tags notmuch-message-queued-tag-changes)
+ (notmuch-tag (car query-and-tags)
+ (cdr query-and-tags))))
+
+(add-hook 'message-send-hook 'notmuch-message-apply-queued-tag-changes)