public static bool ValidateEmailAddress(string emailAddress)
        {
            string pattern = "^((?>[a-zA-Z\\d!#$%&'*+\\-/=?^_`{|}~]+\x20*|\"((?=[\x01-\x7f])[^\"\\]|\\[\x01-\x7f])*\"\x20*)*(?<angle><))?((?!\\.)(?>\\.?[a-zA-Z\\d!#$%&'*+\\-/=?^_`{|}~]+)+|\"((?=[\x01-\x7f])[^\"\\]|\\[\x01-\x7f])*\")@(((?!-)[a-zA-Z\\d\\-]+(?<!-)\\.)+[a-zA-Z]{2,}|\\[(((?(?<!\\[)\\.)(25[0-5]|2[0-4]\\d|[01]?\\d?\\d)){4}|[a-zA-Z\\d\\-]*[a-zA-Z\\d]:((?=[\x01-\x7f])[^\\\\[\\]]|\\[\x01-\x7f])+)\\])(?(angle)>)$";

            if (!String.IsNullOrEmpty(emailAddress) && !(Regex.Match(emailAddress.Trim(), pattern, RegexOptions.IgnoreCase)).Success)
            {
                return false;
            }
            return true;
        }