+
+## How do I search for messages that have no tags?
+
+Unfortunately, there is no way to do this directly.
+
+However, it's possible to accomplish this using two searches in shell. First,
+you need to query all tags in the database, and transform the result into a
+query that matches messages that have none of those tags:
+
+ $ notmuch search --output=tags \* | sed 's/^/not tag:/;2~1s/^/and /'
+
+Next, use that to query the messages:
+
+ $ notmuch search $(notmuch search --output=tags \* | \
+ sed 's/^/not tag:/;2~1s/^/and /')