Email Validation in ASP.net

protected  bool EvaluateIsValid()

    {

        string val = txtEmail.Text;

        string pattern = @"^[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)?@[a-z][a-z|0-9|]*\.([a-z][a-z|0-9]*(\.[a-z][a-z|0-9]*)?)$";

        Match match = Regex.Match(val.Trim(), pattern, RegexOptions.IgnoreCase);

        if (match.Success)

            return true;

        else

            return false;

    }