diff --git a/plugins/libkolab/SQL/mysql.sql b/plugins/libkolab/SQL/mysql.sql
index 55d0dbc9..244ab3d8 100644
--- a/plugins/libkolab/SQL/mysql.sql
+++ b/plugins/libkolab/SQL/mysql.sql
@@ -6,12 +6,15 @@
  * @licence GNU AGPL
  **/
 
-CREATE TABLE IF NOT EXISTS `kolab_cache` (
+DROP TABLE IF EXISTS `kolab_cache`;
+
+CREATE TABLE `kolab_cache` (
   `resource` VARCHAR(255) CHARACTER SET ascii NOT NULL,
   `type` VARCHAR(32) CHARACTER SET ascii NOT NULL,
   `msguid` BIGINT UNSIGNED NOT NULL,
   `uid` VARCHAR(128) CHARACTER SET ascii NOT NULL,
   `created` DATETIME DEFAULT NULL,
+  `changed` DATETIME DEFAULT NULL,
   `data` TEXT NOT NULL,
   `xml` TEXT NOT NULL,
   `dtstart` DATETIME,
diff --git a/plugins/libkolab/lib/kolab_format.php b/plugins/libkolab/lib/kolab_format.php
index 66588975..caae38fd 100644
--- a/plugins/libkolab/lib/kolab_format.php
+++ b/plugins/libkolab/lib/kolab_format.php
@@ -40,6 +40,7 @@ abstract class kolab_format
     protected $loaded = false;
 
     const VERSION = '3.0';
+    const KTYPE_PREFIX = 'application/x-vnd.kolab.';
 
     /**
      * Factory method to instantiate a kolab_format object of the given type
@@ -166,6 +167,17 @@ abstract class kolab_format
         return $vec;
     }
 
+    /**
+     * Parse the X-Kolab-Type header from MIME messages and return the object type in short form
+     *
+     * @param string X-Kolab-Type header value
+     * @return string Kolab object type (contact,event,task,note,etc.)
+     */
+    public static function mime2object_type($x_kolab_type)
+    {
+        return preg_replace('/dictionary.[a-z.]+$/', 'dictionary', substr($x_kolab_type, strlen(self::KTYPE_PREFIX)));
+    }
+
     /**
      * Check for format errors after calling kolabformat::write*()
      *
diff --git a/plugins/libkolab/lib/kolab_storage_cache.php b/plugins/libkolab/lib/kolab_storage_cache.php
index 4e3846dc..004776e0 100644
--- a/plugins/libkolab/lib/kolab_storage_cache.php
+++ b/plugins/libkolab/lib/kolab_storage_cache.php
@@ -215,12 +215,13 @@ class kolab_storage_cache
 
                 $result = $this->db->query(
                     "INSERT INTO kolab_cache ".
-                    " (resource, type, msguid, uid, created, data, xml, dtstart, dtend, tags, words)".
-                    " VALUES (?, ?, ?, ?, " . $this->db->now() . ", ?, ?, ?, ?, ?, ?)",
+                    " (resource, type, msguid, uid, created, changed, data, xml, dtstart, dtend, tags, words)".
+                    " VALUES (?, ?, ?, ?, " . $this->db->now() . ", ?, ?, ?, ?, ?, ?, ?)",
                     $this->resource_uri,
                     $objtype,
                     $msguid,
                     $object['uid'],
+                    $sql_data['changed'],
                     $sql_data['data'],
                     $sql_data['xml'],
                     $sql_data['dtstart'],
@@ -331,7 +332,7 @@ class kolab_storage_cache
                 $index = $this->index;
             }
             else {  // search by object type
-                $search = 'UNDELETED HEADER X-Kolab-Type ' . kolab_storage_folder::KTYPE_PREFIX . $filter['type'];
+                $search = 'UNDELETED HEADER X-Kolab-Type ' . kolab_format::KTYPE_PREFIX . $filter['type'];
                 $index = $this->imap->search_once($this->folder->name, $search)->get();
             }
 
@@ -369,7 +370,7 @@ class kolab_storage_cache
         else {
             // search IMAP by object type
             $filter = $this->_query2assoc($query);
-            $ctype  = kolab_storage_folder::KTYPE_PREFIX . $filter['type'];
+            $ctype  = kolab_format::KTYPE_PREFIX . $filter['type'];
             $index = $this->imap->search_once($this->folder->name, 'UNDELETED HEADER X-Kolab-Type ' . $ctype);
             $count = $index->count();
         }
@@ -464,7 +465,7 @@ class kolab_storage_cache
 
         $results = array();
         foreach ((array)$this->imap->fetch_headers($this->folder->name, $index, false) as $msguid => $headers) {
-            $object_type = preg_replace('/dictionary.[a-z]+$/', 'dictionary', substr($headers->others['x-kolab-type'], strlen(kolab_storage_folder::KTYPE_PREFIX)));
+            $object_type = kolab_format::mime2object_type($headers->others['x-kolab-type']);
 
             // check object type header and abort on mismatch
             if ($type != '*' && $object_type != $type)
@@ -485,7 +486,7 @@ class kolab_storage_cache
     private function _serialize($object)
     {
         $bincols = array_flip($this->binary_cols);
-        $sql_data = array('dtstart' => null, 'dtend' => null, 'xml' => '', 'tags' => '', 'words' => '');
+        $sql_data = array('changed' => null, 'dtstart' => null, 'dtend' => null, 'xml' => '', 'tags' => '', 'words' => '');
         $objtype = $object['_type'] ? $object['_type'] : $this->folder->type;
 
         // set type specific values
@@ -506,6 +507,10 @@ class kolab_storage_cache
                 $sql_data['dtend']   = date('Y-m-d H:i:s', is_object($object['due'])   ? $object['due']->format('U')   : $object['due']);
         }
 
+        if ($object['changed']) {
+            $sql_data['changed'] = date('Y-m-d H:i:s', is_object($object['changed']) ? $object['changed']->format('U') : $object['changed']);
+        }
+
         if ($object['_formatobj']) {
             $sql_data['xml'] = preg_replace('!(</?[a-z0-9:-]+>)[\n\r\t\s]+!ms', '$1', (string)$object['_formatobj']->write());
             $sql_data['tags'] = ' ' . join(' ', $object['_formatobj']->get_tags()) . ' ';  // pad with spaces for strict/prefix search
@@ -581,6 +586,7 @@ class kolab_storage_cache
                 $this->db->quote($msguid),
                 $this->db->quote($object['uid']),
                 $this->db->now(),
+                $this->db->quote($sql_data['changed']),
                 $this->db->quote($sql_data['data']),
                 $this->db->quote($sql_data['xml']),
                 $this->db->quote($sql_data['dtstart']),
@@ -594,7 +600,7 @@ class kolab_storage_cache
         if ($buffer && (!$msguid || (strlen($buffer) + strlen($line) > $this->max_sql_packet))) {
             $result = $this->db->query(
                 "INSERT INTO kolab_cache ".
-                " (resource, type, msguid, uid, created, data, xml, dtstart, dtend, tags, words)".
+                " (resource, type, msguid, uid, created, changed, data, xml, dtstart, dtend, tags, words)".
                 " VALUES $buffer"
             );
             if (!$this->db->affected_rows($result)) {
diff --git a/plugins/libkolab/lib/kolab_storage_folder.php b/plugins/libkolab/lib/kolab_storage_folder.php
index 196e6778..c7a045f4 100644
--- a/plugins/libkolab/lib/kolab_storage_folder.php
+++ b/plugins/libkolab/lib/kolab_storage_folder.php
@@ -23,8 +23,6 @@
  */
 class kolab_storage_folder
 {
-    const KTYPE_PREFIX = 'application/x-vnd.kolab.';
-
     /**
      * The folder name.
      * @var string
@@ -358,7 +356,7 @@ class kolab_storage_folder
             if ($param[0] == 'type') {
                 $type = $param[2];
             }
-            else if (($param[0] == 'dtstart' || $param[0] == 'dtend') && is_numeric($param[2])) {
+            else if (($param[0] == 'dtstart' || $param[0] == 'dtend' || $param[0] == 'changed') && is_numeric($param[2])) {
               $query[$i][2] = date('Y-m-d H:i:s', $param[2]);
             }
         }
@@ -428,8 +426,8 @@ class kolab_storage_folder
         $this->imap->set_folder($folder);
 
         $headers = $this->imap->get_message_headers($msguid);
-        $object_type = preg_replace('/dictionary.[a-z]+$/', 'dictionary', substr($headers->others['x-kolab-type'], strlen(self::KTYPE_PREFIX)));
-        $content_type  = self::KTYPE_PREFIX . $object_type;
+        $object_type = kolab_format::mime2object_type($headers->others['x-kolab-type']);
+        $content_type  = kolab_format::KTYPE_PREFIX . $object_type;
 
         // check object type header and abort on mismatch
         if ($type != '*' && $object_type != $type)
@@ -719,7 +717,7 @@ class kolab_storage_folder
             $headers['To'] = $ident['email'];
         }
         $headers['Date'] = date('r');
-        $headers['X-Kolab-Type'] = self::KTYPE_PREFIX . $type;
+        $headers['X-Kolab-Type'] = kolab_format::KTYPE_PREFIX . $type;
         $headers['X-Kolab-Mime-Version'] = kolab_format::VERSION;
         $headers['Subject'] = $object['uid'];
 //        $headers['Message-ID'] = $rcmail->gen_message_id();