+
+ <b>index.decrypt</b> <b>[STORED</b> <b>IN</b> <b>DATABASE]</b>
+ Policy for decrypting encrypted messages during indexing. Must
+ be one of: <b>false</b>, <b>auto</b>, <b>nostash</b>, or <b>true</b>.
+
+ When indexing an encrypted e-mail message, if this variable is
+ set to <b>true</b>, notmuch will try to decrypt the message and index
+ the cleartext, stashing a copy of any discovered session keys
+ for the message. If <b>auto</b>, 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 <b>false</b> to avoid decrypting even when a stashed session
+ key is already present.
+
+ <b>nostash</b> is the same as <b>true</b> except that it will not stash
+ newly-discovered session keys in the database.
+
+ From the command line (i.e. during <a href='../notmuch-new-1/'>notmuch-new</a>(1), <a href='../notmuch-insert-1/'>not‐</a>
+ <a href='../notmuch-insert-1/'>much-insert</a>(1), or <a href='../notmuch-reindex-1/'>notmuch-reindex</a>(1)), the user can override
+ the database's stored decryption policy with the <b>--decrypt=</b>
+ option.
+
+ Here is a table that summarizes the functionality of each of
+ these policies:
+
+ ┌──────────────┬───────┬──────┬─────────┬──────┐
+ │ │ false │ auto │ nostash │ true │
+ ├──────────────┼───────┼──────┼─────────┼──────┤
+ │Index cleart‐ │ │ X │ X │ X │
+ │ext using │ │ │ │ │
+ │stashed ses‐ │ │ │ │ │
+ │sion keys │ │ │ │ │
+ ├──────────────┼───────┼──────┼─────────┼──────┤
+ │Index cleart‐ │ │ │ X │ X │
+ │ext using │ │ │ │ │
+ │secret keys │ │ │ │ │
+ ├──────────────┼───────┼──────┼─────────┼──────┤
+ │Stash session │ │ │ │ X │
+ │keys
+ ├──────────────┼───────┼──────┼─────────┼──────┤
+ │Delete
+ │stashed ses‐ │ │ │ │ │
+ │sion keys on │ │ │ │ │
+ │reindex │ │ │ │ │
+ └──────────────┴───────┴──────┴─────────┴──────┘
+
+ Stashed session keys are kept in the database as properties
+ associated with the message. See <b>session-key</b> in <a href='../notmuch-properties-7/'>notmuch-proper‐</a>
+ <a href='../notmuch-properties-7/'>ties</a>(7) for more details about how they can be useful.
+
+ Be aware that the notmuch index is likely sufficient (and a
+ stashed session key is certainly sufficient) to reconstruct the
+ cleartext of the message itself, so please ensure that the not‐
+ much message index is adequately protected. DO NOT USE
+ <b>index.decrypt=true</b> or <b>index.decrypt=nostash</b> without considering
+ the security of your index.
+
+ Default: <b>auto</b>.
+
+ <b>index.header.<prefix></b> <b>[STORED</b> <b>IN</b> <b>DATABASE]</b>
+ Define the query prefix <prefix>, based on a mail header. For
+ example <b>index.header.List=List-Id</b> will add a probabilistic pre‐
+ fix <b>List:</b> that searches the <b>List-Id</b> field. User defined pre‐
+ fixes must not start with 'a'...'z'; in particular adding a pre‐
+ fix with same name as a predefined prefix is not supported. See
+ <a href='../notmuch-search-terms-7/'>notmuch-search-terms</a>(7) for a list of existing prefixes, and an
+ explanation of probabilistic prefixes.
+
+ <b>built</b>_<b>with.<name></b>
+ Compile time feature <name>. Current possibilities include "com‐
+ pact" (see <a href='../notmuch-compact-1/'>notmuch-compact</a>(1)) and "field_processor" (see <a href='../notmuch-search-terms-7/'>not‐</a>
+ <a href='../notmuch-search-terms-7/'>much-search-terms</a>(7)).
+
+ <b>query.<name></b> <b>[STORED</b> <b>IN</b> <b>DATABASE]</b>
+ Expansion for named query called <name>. See <a href='../notmuch-search-terms-7/'>not‐</a>
+ <a href='../notmuch-search-terms-7/'>much-search-terms</a>(7) for more information about named queries.