Hide my Code ?

i have create a simple dll file called Mail_client.dll for send mail .when i use this dll file i can create a object from the class Mail and send mail (support for multiple smtp clients)

using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using Mail_Client_by_kalana;
using System.Windows.Forms;

namespace testclass
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Mail mymail = new Mail("myemailaddress@yahoo.com", "mypassword", "sender_emailaddress");
            mymail.WriteMail("email_sibject", "my message here");
            
        }
    }
}

my dll file automatic recognize host and config smtp settings related to host and send the mail..works like a charm
heres my problem when i do this

 Mail mymail = new Mail("[b]myemailaddress@aaawa.com[/b]", "mypassword", "sender_emailaddress");
            mymail.WriteMail("email_sibject", "my message here");

when i made a mistake (eg.. invalid email) its directly go to my class (code) and display the line
i want to hide my code in mynamespace.
how can i do it..thanks in advance ..sorry for my bad english