diff --git a/server/services/monitoringService.js b/server/services/monitoringService.js
index e962460..ba03ea6 100644
--- a/server/services/monitoringService.js
+++ b/server/services/monitoringService.js
@@ -22,6 +22,9 @@ angular.module('ffffng')
 ) {
     var MONITORING_STATE_MACS_CHUNK_SIZE = 100;
     var MONITORING_MAILS_DB_BATCH_SIZE = 50;
+    /**
+     * Defines the intervals emails are sent if a node is offline
+     */
     var MONITORING_OFFLINE_MAILS_SCHEDULE = {
         1: { amount: 3, unit: 'hours' },
         2: { amount: 1, unit: 'days' },
@@ -343,11 +346,20 @@ angular.module('ffffng')
         );
     }
 
+    /**
+     * sends one of three mails if a node is offline
+     * @param  {moment}   startTime  the moment the job started
+     * @param  {Number}   mailNumber which of three mails
+     * @param  {Function} callback   gets all nodes that are offline
+     */
     function sendOfflineMails(startTime, mailNumber, callback) {
         sendMonitoringMailsBatched(
             'offline ' + mailNumber,
             'monitoring-offline-' + mailNumber,
             function (findBatchCallback) {
+                /**
+                 * descriptive string that stores, which was the last mail type, stored in the database as last_status_mail_type
+                 */
                 var previousType =
                     mailNumber === 1
                         ? 'monitoring-online-again'