using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(IsValidEmailAddress("vorname.nachname@gmx.at"));

    }

    public static bool IsValidEmailAddress(string email)

    {

        try

        {

            var addr = new System.Net.Mail.MailAddress(email);

            return addr.Address == email

                && !email.Contains("ü")

                && !email.Contains("Ü")

                && !email.Contains("ö")

                && !email.Contains("Ö")

                && !email.Contains("ä")

                && !email.Contains("Ä")

                && !email.Contains("ß");

        }

        catch (Exception)

        {

            return false;

        }

    }

}