- attachment:<word>
+- mimetype:<word>
+
- tag:<tag> (or is:<tag>)
- id:<message-id>
The **attachment:** prefix can be used to search for specific filenames
(or extensions) of attachments to email messages.
+The **mimetype:** prefix will be used to match text from the
+content-types of MIME parts within email messages (as specified by the
+sender).
+
For **tag:** and **is:** valid tag values include **inbox** and
**unread** by default for new messages added by **notmuch new** as well
as any other tag values added manually with **notmuch tag**.