IsEmail extension method

IsEmail.cs

public static bool IsValidEmail(string email)
    {
        string pattern = @"^(([^<>()[\]\\.,;:\s@\""]+"
                            + @"(\.[^<>()[\]\\.,;:\s@\""]+)*)|(\"".+\""))@"
                            + @"((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"
                            + @"\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+"
                            + @"[a-zA-Z]{2,}))$";
        Regex regex = new Regex(pattern);
        return regex.IsMatch(email);
    }