diff --git a/imap-core/test/imap-compiler-test.js b/imap-core/test/imap-compiler-test.js
index 9098ed36..05f1a9c3 100644
--- a/imap-core/test/imap-compiler-test.js
+++ b/imap-core/test/imap-compiler-test.js
@@ -69,6 +69,7 @@ describe('IMAP Command Compiler', function() {
         describe('ATOM', function() {
             it('should compile correctly', function() {
                 parsed.attributes = [
+                    //
                     {
                         type: 'ATOM',
                         value: 'ALERT'
diff --git a/imap.js b/imap.js
index 69712fef..09ec61d0 100644
--- a/imap.js
+++ b/imap.js
@@ -22,7 +22,7 @@ const packageData = require('./package.json');
 const BULK_BATCH_SIZE = 150;
 
 // how often to clear expired messages
-const GC_INTERVAL = 1 * 60 * 1000;
+const GC_INTERVAL = 60 * 60 * 1000;
 
 // Setup server
 const serverOptions = {
@@ -1970,7 +1970,7 @@ function clearExpiredMessages() {
     clearTimeout(gcTimeout);
 
     // First, acquire the lock. This prevents multiple connected clients for deleting the same messages
-    gcLock.acquireLock('gc_expired', 10 * 60 * 1000 /* Lock expires after 10min if not released */, (err, lock) => {
+    gcLock.acquireLock('gc_expired', 61 * 60 * 1000 /* Lock expires after 61min if not released */, (err, lock) => {
         if (err) {
             server.logger.error(
                 {
diff --git a/lib/message-handler.js b/lib/message-handler.js
index d3ad6c94..a8e9cea4 100644
--- a/lib/message-handler.js
+++ b/lib/message-handler.js
@@ -14,21 +14,8 @@ const counters = require('./counters');
 const BULK_BATCH_SIZE = 150;
 const SCHEMA_VERSION = '1.0';
 
-// header prefixes that are skipped when building index
-const IGNORE_HEADERS = [
-    'arc-',
-    'authentication-',
-    'content-',
-    'dkim-',
-    'list-',
-    'mime-',
-    'received',
-    'x-gm-',
-    'x-google-',
-    'x-original-',
-    'x-originating-',
-    'x-received'
-];
+// index only the following headers for SEARCH
+const INDEXED_HEADERS = ['to', 'cc', 'subject', 'from', 'sender', 'reply-to', 'message-id', 'thread-index'];
 
 class MessageHandler {
     constructor(database, redisConfig) {
@@ -726,7 +713,7 @@ class MessageHandler {
 
                 let key = line.substr(0, line.indexOf(':')).trim().toLowerCase();
 
-                if (IGNORE_HEADERS.find(prefix => key.indexOf(prefix) === 0)) {
+                if (!INDEXED_HEADERS.includes(key)) {
                     // do not index this header
                     return false;
                 }