diff --git a/doc/man1/notmuch-config.rst b/doc/man1/notmuch-config.rst
index 1a9e08a3..dabf269f 100644
--- a/doc/man1/notmuch-config.rst
+++ b/doc/man1/notmuch-config.rst
@@ -143,10 +143,12 @@ The available configuration items are described below.
         **[STORED IN DATABASE]**
         When indexing an encrypted e-mail message, if this variable is
         set to ``true``, notmuch will try to decrypt the message and
-        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.
 
         Be aware that the notmuch index is likely sufficient to
         reconstruct the cleartext of the message itself, so please
diff --git a/doc/man1/notmuch-insert.rst b/doc/man1/notmuch-insert.rst
index b22be863..214f261b 100644
--- a/doc/man1/notmuch-insert.rst
+++ b/doc/man1/notmuch-insert.rst
@@ -54,12 +54,13 @@ Supported options for **insert** include
     ``--decrypt=(true|auto|false)``
 
         If ``true`` and the message is encrypted, try to decrypt the
-        message while indexing.  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).
+        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
diff --git a/doc/man1/notmuch-new.rst b/doc/man1/notmuch-new.rst
index 71df31d7..27676a19 100644
--- a/doc/man1/notmuch-new.rst
+++ b/doc/man1/notmuch-new.rst
@@ -46,16 +46,17 @@ Supported options for **new** include
     ``--decrypt=(true|auto|false)``
 
         If ``true``, when encountering an encrypted message, try to
-        decrypt it while indexing.  If decryption is successful, index
-        the cleartext itself.  If ``auto``, try to use any session key
-        already known to belong to this message, but do not attempt to
-        use the user's secret keys.
+        decrypt it while indexing, and store any discovered session
+        keys.  If ``auto``, try to use any session key already known
+        to belong to this message, but do not attempt to use the
+        user's secret keys.  If decryption is successful, index the
+        cleartext of the message.
 
-        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.
+        Be aware that the index is likely sufficient (and the session
+        key is certainly 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)**.
 
diff --git a/doc/man1/notmuch-reindex.rst b/doc/man1/notmuch-reindex.rst
index e8174f39..47790871 100644
--- a/doc/man1/notmuch-reindex.rst
+++ b/doc/man1/notmuch-reindex.rst
@@ -24,11 +24,11 @@ Supported options for **reindex** include
     ``--decrypt=(true|auto|false)``
 
         If ``true``, when encountering an encrypted message, try to
-        decrypt it while reindexing.  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.
+        decrypt it while reindexing, 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.
 
         If ``false``, notmuch reindex will also delete any stashed
         session keys for all messages matching the search terms.
diff --git a/doc/man7/notmuch-properties.rst b/doc/man7/notmuch-properties.rst
index 1a3f690e..07d36a1a 100644
--- a/doc/man7/notmuch-properties.rst
+++ b/doc/man7/notmuch-properties.rst
@@ -98,6 +98,10 @@ of its normal activity.
     message.  This includes attachments, cryptographic signatures, and
     other material that cannot be reconstructed from the index alone.
 
+    See ``index.decrypt`` in **notmuch-config(1)** for more
+    details about how to set notmuch's policy on when to store session
+    keys.
+
     The session key should be in the ASCII text form produced by
     GnuPG.  For OpenPGP, that consists of a decimal representation of
     the hash algorithm used (identified by number from RFC 4880,
diff --git a/lib/index.cc b/lib/index.cc
index 3914012a..0ad683fa 100644
--- a/lib/index.cc
+++ b/lib/index.cc
@@ -549,11 +549,15 @@ _index_encrypted_mime_part (notmuch_message_t *message,
     }
 #endif
     bool attempted = false;
+    GMimeDecryptResult *decrypt_result = NULL;
+    bool get_sk = (HAVE_GMIME_SESSION_KEYS && notmuch_indexopts_get_decrypt_policy (indexopts) == NOTMUCH_DECRYPT_TRUE);
     clear = _notmuch_crypto_decrypt (&attempted, notmuch_indexopts_get_decrypt_policy (indexopts),
-				     message, crypto_ctx, encrypted_data, NULL, &err);
+				     message, crypto_ctx, encrypted_data, get_sk ? &decrypt_result : NULL, &err);
     if (!attempted)
 	return;
     if (err || !clear) {
+	if (decrypt_result)
+	    g_object_unref (decrypt_result);
 	if (err) {
 	    _notmuch_database_log (notmuch, "Failed to decrypt during indexing. (%d:%d) [%s]\n",
 				   err->domain, err->code, err->message);
@@ -568,6 +572,18 @@ _index_encrypted_mime_part (notmuch_message_t *message,
 					  "property (%d)\n", status);
 	return;
     }
+    if (decrypt_result) {
+#if HAVE_GMIME_SESSION_KEYS
+	if (get_sk) {
+	    status = notmuch_message_add_property (message, "session-key",
+						   g_mime_decrypt_result_get_session_key (decrypt_result));
+	    if (status)
+		_notmuch_database_log (notmuch, "failed to add session-key "
+				       "property (%d)\n", status);
+	}
+#endif
+	g_object_unref (decrypt_result);
+    }
     _index_mime_part (message, indexopts, clear);
     g_object_unref (clear);
 
diff --git a/test/T357-index-decryption.sh b/test/T357-index-decryption.sh
index 9f46a01b..fcecb1d9 100755
--- a/test/T357-index-decryption.sh
+++ b/test/T357-index-decryption.sh
@@ -48,6 +48,17 @@ test_expect_equal \
     "$output" \
     "$expected"
 
+test_begin_subtest "show the message body of the encrypted message"
+notmuch dump wumpus
+output=$(notmuch show wumpus | awk '/^\014part}/{ f=0 }; { if (f) { print $0 } } /^\014part{ ID: 3/{ f=1 }')
+expected='This is a test encrypted message with a wumpus.'
+if [ $NOTMUCH_HAVE_GMIME_SESSION_KEYS -eq 0 ]; then
+    test_subtest_known_broken
+fi
+test_expect_equal \
+    "$output" \
+    "$expected"
+
 
 test_begin_subtest "message should go away after deletion"
 # cache the message in an env var and remove it:
@@ -129,10 +140,21 @@ test_expect_equal \
     "$output" \
     "$expected"
 
+# try a simple reindex
+test_begin_subtest 'reindex in auto mode'
+test_expect_success 'notmuch reindex tag:encrypted and property:index.decryption=success'
+test_begin_subtest "reindexed encrypted messages, should not have changed"
+output=$(notmuch search wumpus)
+if [ $NOTMUCH_HAVE_GMIME_SESSION_KEYS -eq 0 ]; then
+    test_subtest_known_broken
+fi
+test_expect_equal \
+    "$output" \
+    "$expected"
 
 # try to remove cleartext indexing
 test_begin_subtest 'reindex without cleartext'
-test_expect_success 'notmuch reindex tag:encrypted and property:index.decryption=success'
+test_expect_success 'notmuch reindex --decrypt=false tag:encrypted and property:index.decryption=success'
 test_begin_subtest "reindexed encrypted messages, without cleartext"
 output=$(notmuch search wumpus)
 expected=''
diff --git a/util/crypto.c b/util/crypto.c
index 338f1d5d..066dea6e 100644
--- a/util/crypto.c
+++ b/util/crypto.c
@@ -197,10 +197,24 @@ _notmuch_crypto_decrypt (bool *attempted,
     if (attempted)
 	*attempted = true;
 #if (GMIME_MAJOR_VERSION < 3)
+#if HAVE_GMIME_SESSION_KEYS
+    gboolean oldgetsk = g_mime_crypto_context_get_retrieve_session_key (crypto_ctx);
+    gboolean newgetsk = (decrypt_result);
+    if (newgetsk != oldgetsk)
+	/* This could return an error, but we can't do anything about it, so ignore it */
+	g_mime_crypto_context_set_retrieve_session_key (crypto_ctx, newgetsk, NULL);
+#endif
     ret = g_mime_multipart_encrypted_decrypt(part, crypto_ctx,
 					     decrypt_result, err);
+#if HAVE_GMIME_SESSION_KEYS
+    if (newgetsk != oldgetsk)
+	g_mime_crypto_context_set_retrieve_session_key (crypto_ctx, oldgetsk, NULL);
+#endif
 #else
-    ret = g_mime_multipart_encrypted_decrypt(part, GMIME_DECRYPT_NONE, NULL,
+    GMimeDecryptFlags flags = GMIME_DECRYPT_NONE;
+    if (decrypt_result)
+	flags |= GMIME_DECRYPT_EXPORT_SESSION_KEY;
+    ret = g_mime_multipart_encrypted_decrypt(part, flags, NULL,
 					     decrypt_result, err);
 #endif
     return ret;