diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index 812bf492..20f6cf41 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -2446,9 +2446,16 @@ function rcube_calendar_ui(settings)
         }
 
         // submit status change to server
-        var submit_data = $.extend({}, me.selected_event, { source:null, comment:$('#reply-comment-event-rsvp').val(), _savemode: replymode || 'all' }, (delegate || {})),
+        var submit_data = $.extend({}, { source:null, comment:$('#reply-comment-event-rsvp').val(), _savemode: replymode || 'all' }, (delegate || {})),
+          submit_items = 'id,uid,_instance,calendar,_mbox,_uid,_part,attendees,free_busy,allDay',
           noreply = $('#noreply-event-rsvp:checked').length ? 1 : 0;
 
+        // Submit only that data we really need
+        $.each(submit_items.split(','), function() {
+          if (this in me.selected_event)
+            submit_data[this] = me.selected_event[this];
+        });
+
         // import event from mail (temporary iTip event)
         if (submit_data._mbox && submit_data._uid) {
           me.saving_lock = rcmail.set_busy(true, 'calendar.savingdata');
diff --git a/plugins/libkolab/lib/kolab_date_recurrence.php b/plugins/libkolab/lib/kolab_date_recurrence.php
index 2ec06c8a..5ab4532e 100644
--- a/plugins/libkolab/lib/kolab_date_recurrence.php
+++ b/plugins/libkolab/lib/kolab_date_recurrence.php
@@ -32,6 +32,9 @@ class kolab_date_recurrence
     private /* DateTime */ $next;
     private /* cDateTime */ $cnext;
     private /* DateInterval */ $duration;
+    private /* string */ $start_time;
+    private /* string */ $end_time;
+
 
     /**
      * Default constructor
@@ -47,6 +50,13 @@ class kolab_date_recurrence
         $this->start  = $this->next = $data['start'];
         $this->cnext  = kolab_format::get_datetime($this->next);
 
+        if ($this->start && !empty($data['allday'])) {
+            $this->start_time = $data['start']->format('H:i:s');
+            if ($data['end']) {
+                $this->end_time = $data['end']->format('H:i:s');
+            }
+        }
+
         if (is_object($data['start']) && is_object($data['end'])) {
             $this->duration = $data['start']->diff($data['end']);
         }
@@ -91,7 +101,21 @@ class kolab_date_recurrence
             $next_end = clone $next_start;
             $next_end->add($this->duration);
 
-            $next          = $this->object->to_array();
+            $next = $this->object->to_array();
+
+            // it looks that for allday events the occurrence time
+            // is reset to 00:00:00, this is causing various issues
+            if (!empty($next['allday'])) {
+                if ($this->start_time) {
+                    $time = explode(':', $this->start_time);
+                    $next_start->setTime((int)$time[0], (int)$time[1], (int)$time[2]);
+                }
+                if ($this->start_end) {
+                    $time = explode(':', $this->start_end);
+                    $next_end->setTime((int)$time[0], (int)$time[1], (int)$time[2]);
+                }
+            }
+
             $next['start'] = $next_start;
             $next['end']   = $next_end;