Sending Email using net.mail

Hi,
I have an email class using net.mail. I want to be able to send multiple emails for weekly newsletters. I add recipients using AddRecipeint method then build the recipient list using BuildRecipientList(). This all works fine, however the problem is that each email displays all recipients in the To: address list. Obviously I only want to have the recipients email shown. Can anyone tell me how to hide all other recipients except the reciever or if there is a better way of sending to multiple users?

        public void AddRecipient(string EmailAddress)
        {
            arToAddresses.Add(EmailAddress);
        }
         private void BuildRecipientList(MailMessage Mailer)
        {
     & ...