allowed MailDataModel without link to account

account/src/main/java/de/muehlencord/shared/account/business/mail/MailDatamodel.java

@@ -13,6 +13,11 @@ public class MailDatamodel {
     private final AccountEntity account;
     private final Map<String,String> parameter;
 
+    public MailDatamodel() {
+        this.account = null;
+        this.parameter = new HashMap<>();
+    }
+        
     public MailDatamodel(AccountEntity account) {
         this.parameter = new HashMap<>();
         this.account = account;