diff --git a/config.inc.php.dist b/config.inc.php.dist
index 592ca5a..08d9611 100644
--- a/config.inc.php.dist
+++ b/config.inc.php.dist
@@ -143,6 +143,20 @@ $config['kolab_invitation_calendars'] = false;
 // %i - Calendar UUID
 // $config['calendar_caldav_url'] = 'http://%h/iRony/calendars/%u/%i';
 
+// List of CalDAV sources that should be allready installed.
+// They will be added when the calendar section is accessed for the first time by a user.
+// For 'caldav_user' and 'caldav_url' the following replacement variables are supported:
+// %u - Current webmail user name
+// For 'caldav_pass' %p is replaced by the current user's password.
+// $config['calendar_caldav_preinstalled_sources'] = array(
+//     'name' => array(
+//         'caldav_user' => '%u',
+//         'caldav_pass' => '%p',
+//         'caldav_url'  => 'https://example.net/dav',
+//         'showAlarms'  => 1
+//     )
+// );
+
 // Driver to provide a resource directory ('ldap' is the only implementation yet).
 // Leave empty or commented to disable resources support.
 // $config['calendar_resources_driver'] = 'ldap';
diff --git a/drivers/caldav/caldav_driver.php b/drivers/caldav/caldav_driver.php
index 14bbae3..d7df23f 100644
--- a/drivers/caldav/caldav_driver.php
+++ b/drivers/caldav/caldav_driver.php
@@ -101,9 +101,41 @@ class caldav_driver extends calendar_driver
         if(self::$debug === null)
             self::$debug = $this->rc->config->get('calendar_caldav_debug', False);
 
+        $this->_setup_preinstalled_sources();
         $this->_read_calendars();
     }
 
+    /**
+     * Setup preinstalled sources defined in config file
+     */
+    protected function _setup_preinstalled_sources()
+    {
+        $preinstalled_sources = $this->rc->config->get('calendar_caldav_preinstalled_sources', FALSE);
+        if ($preinstalled_sources && is_array($preinstalled_sources)) {
+            $username = $this->rc->get_user_name();
+            $password = $this->rc->get_user_password();
+
+            foreach ($preinstalled_sources as $cal){
+                $url  = $cal['caldav_url'];
+                $user = $cal['caldav_user'];
+                $pass = $cal['caldav_pass'];
+
+                $url  = str_replace('%u', $username, $url);
+                $user = str_replace('%u', $username, $user);
+                $pass = str_replace('%p', $password, $pass);
+
+                $cal['caldav_url']  = $url;
+                $cal['caldav_user'] = $user;
+                $cal['caldav_pass'] = $pass;
+
+                if (!$this->create_source($cal)) {
+                    $error_msg = 'Unable to add default calendars' . ($this->last_error ? ': ' . $this->last_error :'');
+                    $this->rc->output->show_message($error_msg, 'error');
+                }
+            }
+        }
+    }
+
     /**
      * Read available calendars for the current user and store them internally
      */
@@ -302,6 +334,10 @@ class caldav_driver extends calendar_driver
     {
         $source['caldav_url'] = self::_encode_url($source['caldav_url']);
 
+        // Skip already exiting sources
+        $result = $this->rc->db->query("SELECT user_id, caldav_url, caldav_user FROM " . $this->db_sources . " WHERE user_id=? AND caldav_url=? AND caldav_user=?", $this->rc->user->ID, $source['caldav_url'], $source['caldav_user']);
+        if($this->rc->db->affected_rows($result)) return true;
+
         try {
             $calendars = $this->_autodiscover_calendars($source);
         }