- index the cleartext. If ``auto``, it will try to index the
- cleartext if a stashed session key is already known for the message,
- but will not try to access your secret keys. Use ``false`` to
- avoid decrypting even when a session key is already known.
+ index the cleartext, stashing a copy of any discovered session
+ keys for the message. If ``auto``, it will try to index the
+ cleartext if a stashed session key is already known for the message
+ (e.g. from a previous copy), but will not try to access your
+ secret keys. Use ``false`` to avoid decrypting even when a
+ stashed session key is already present.