邮件发送(第一次点击按钮不响应)

Question

这是全部代码: 
问题是:我运行点击按钮后,第一次发送提示成功发送,但是邮箱中无信息,你在点击第二次,第三次,邮箱中都有信息,这下晕了,高手们,希望 > > > >?????? 
    DataSet ds = new DataSet(); 
    public int resultCount = 0; 
    protected void Page_Load(object sender, EventArgs e) 
    { 
            OleDbConnection cn = new OleDbConnection(System.Configuration.ConfigurationManager.ConnectionStrings["con"].ConnectionString); 
            OleDbCommand cmd = new OleDbCommand("select count(*) from email", cn); 
            cn.Open(); 
            resultCount = Convert.ToInt32(cmd.ExecuteScalar()); 
            cn.Close();             OleDbDataAdapter dr = new OleDbDataAdapter("select email from email", cn); 
            cn.Open(); 
            dr.Fill(ds); 
            cn.Close(); 
    } 
    //群发邮件 
    private void SendMyMail() 
    { 
        string FromMail = "[email protected]";     //发件人 
        string Title = txtName.Text;   //   邮件主题 
        string Body = txtMessage.Text;   //邮件主体         string MailUserName = "liyou502";       //FromMail.Substring(0, FromMail.IndexOf( '@ ')); 
        string MailPassword = "****";     //发件人邮箱密码         MailMessage mailmessage = new MailMessage(); 
        MailAddress n = new MailAddress(FromMail);         mailmessage.From = n; 
        mailmessage.Subject = Title; 
        mailmessage.Body = Body;         System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(); 
        client.Host = "smtp.163.com"; 
        client.Credentials = new System.Net.NetworkCredential(MailUserName, MailPassword);   
        try 
        { 
            string[] Receiver = new string[resultCount];//resultCount为数据库中的行数(无空值) 
            for (int i = 0; i  < resultCount; i++) 
            { 
                Receiver[i] = ds.Tables[0].Rows[i]["email"].ToString(); 
            } 
            for (int i = 0; i  < resultCount; i++) 
            { 
                if (Receiver[i] == "") 
                { 
                    Receiver[i] = "[email protected]"; 
                } 
                MailAddress to = new MailAddress(Receiver[i].ToString()); 
                mailmessage.To.Add(to); 
                client.Send(mailmessage); 
                mailmessage.To.Clear(); 
                Response.Write("成功发送!"); 
            } 
        } 
        catch (Exception) 
        { 
            Response.Write(" <script language= 'javascript ' >alert( '邮件发送失败! ') </script >"); 
        } 
    } 
   protected void btnSubmit_Click(object sender, EventArgs e) 
    { 
        SendMyMail(); 
        //Response.Write(" <script >alert ( 'Email envoyé avec succès ! ');location.href= 'index.aspx '; </script >");     } 
}