diff --git a/calendar/js/app.js b/calendar/js/app.js
index 1d537f7ca5..1674cd2598 100644
--- a/calendar/js/app.js
+++ b/calendar/js/app.js
@@ -3688,7 +3688,7 @@ var CalendarApp = /** @class */ (function (_super) {
             // Send just the timestamp (as a string) with no timezone
             (typeof _data.start != "string" ? _data.start.toJSON() : _data.start).slice(0, -1),
             (typeof _data.end != "string" ? _data.end.toJSON() : _data.end).slice(0, -1), {
-                participants: Object.keys(_data.participants).filter(function (v) { return v.match(/^[0-9]/); })
+                participants: Object.keys(_data.participants).filter(function (v) { return v.match(/^[0-9]|[e]/); })
             }], function (_value) {
             if (_value) {
                 if (_value.err)
diff --git a/calendar/js/app.ts b/calendar/js/app.ts
index 1087957858..dbb7aa72c6 100644
--- a/calendar/js/app.ts
+++ b/calendar/js/app.ts
@@ -4577,7 +4577,7 @@ class CalendarApp extends EgwApp
 				( typeof _data.start != "string" ? _data.start.toJSON() : _data.start).slice(0,-1),
                 ( typeof _data.end != "string" ? _data.end.toJSON() : _data.end).slice(0,-1),
 				{
-					participants:Object.keys(_data.participants).filter(v => {return v.match(/^[0-9]/)})
+					participants:Object.keys(_data.participants).filter(v => {return v.match(/^[0-9]|[e]/)})
 				}], function(_value){
 					if (_value)
 					{