+ ``--keep``
+ Keep the message file if indexing fails, and keep the message
+ indexed if applying tags or maildir flag synchronization
+ fails. Ignore these errors and return exit status 0 to
+ indicate successful mail delivery.
+
+ ``--no-hooks``
+ Prevent hooks from being run.
+
+ ``--decrypt=(true|auto|false)``
+
+ If ``true`` and the message is encrypted, try to decrypt the
+ message while indexing, storing any session keys discovered.
+ If ``auto``, and notmuch already knows about a session key for
+ the message, it will try decrypting using that session key but
+ will not try to access the user's secret keys. If decryption
+ is successful, index the cleartext itself. Either way, the
+ message is always stored to disk in its original form
+ (ciphertext).
+
+ Be aware that the index is likely sufficient to reconstruct
+ the cleartext of the message itself, so please ensure that the
+ notmuch message index is adequately protected. DO NOT USE
+ ``--decrypt=true`` without considering the security of
+ your index.
+
+ See also ``index.decrypt`` in **notmuch-config(1)**.
+