diff --git a/messages/src/main/java/de/srsoftware/umbrella/message/MessageSystem.java b/messages/src/main/java/de/srsoftware/umbrella/message/MessageSystem.java
index 9e6cca9a..787ec3b1 100644
--- a/messages/src/main/java/de/srsoftware/umbrella/message/MessageSystem.java
+++ b/messages/src/main/java/de/srsoftware/umbrella/message/MessageSystem.java
@@ -40,6 +40,7 @@ import jakarta.mail.internet.MimeMultipart;
 import jakarta.mail.util.ByteArrayDataSource;
 import java.io.IOException;
 import java.time.ZoneId;
+import java.time.ZoneOffset;
 import java.util.*;
 import org.json.JSONArray;
 import org.json.JSONObject;
@@ -329,7 +330,7 @@ public class MessageSystem extends BaseHandler implements PostBox, EventListener
 
 		var sender  = message.sender().name();
 		var subject = message.subject();
-		var time    = envelope.time().atZone(ZoneId.systemDefault()).format(TIME_FORMATTER);
+		var time    = envelope.time().atZone(ZoneOffset.UTC).format(TIME_FORMATTER);
 		var id      = envelope.id();
 		return new JSONObject(Map.of(SENDER,sender,SUBJECT,subject,TIMESTAMP,time,ID,id));
 	}