fix buggy typo introduced in last commit

Author: NickOvt

lib/handlers/on-search.js

@@ -271,7 +271,7 @@ module.exports = server => (mailbox, options, session, callback) => {
                                     hdate: !ne
                                         ? entry
                                         : {
-                                              $not: {}
+                                              $not: entry
                                           }
                                 };