public static bool ValidateEMail(string email)
{
    if (email == null || email == "") return false;

    Regex oRegExp = new Regex(@"^[A-Za-z0-9_.\-]+@[A-Za-z0-9_\-]+\.([A-Za-z0-9_\-]+\.)*[A-Za-z][A-Za-z]+$", RegexOptions.IgnoreCase);
    return oRegExp.Match(email).Success;
}