I am new to ASP.NET (only coded web pages in HTML in the past), and I'm
having some trouble: I have a form on which a visitor to my page can
fill out comments and send them to my E-mail box.  The code works fine
when I test it on my local machine; but for the identical code deployed
to my web site (hosted on GoDaddy.com), when I click the "Submit" button
to send the E-mail, an exception is thrown containing the following
error:

Request for the permission of type 'System.Net.Mail.SmtpPermission,
System, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089' failed.

I don't have the slightest idea when this means.  I'm using the Express
version of VS 2008, so I cannot remotely debug the code.  Does anyone
have any idea what's wrong?  Here are the relevant code snippets:

Contact.aspx
---------------------
<table cellspacing="0" cellpadding="5" bgcolor="#ffe0c0">
   <tbody>
       <!-- (Other fields for E-mail address, etc. not shown) -->
       <tr>
           <td align="right">
               <font face="Arial">&nbsp;Write your message
                             here:font>
           </td>
           <td>
               <asp:TextBox id="TB_EmailBody" runat="server"
                    Font-Names="Arial" Width="400px"
                    TextMode="MultiLine" Height="100px" Rows="5">
               </asp:TextBox>
               <asp:RequiredFieldValidator ID="RFV_EmailBody"
                             runat="server"
                             ControlToValidate="TB_EmailBody"
                             SetFocusOnError="true" />
           </td>
       </tr>
       <tr>
           <td align="center">
               <asp:Button id="SubmitButton"
                   OnClick="SendFeedbackEmail" runat="server"
                   Text="Submit"
                   Style="z-index: 100; left: -35px; position:
                   relative; top: 0px" Width="150px" />
           </td>
       </tr>
             
       <tr>
           <td colspan="2">
               <asp:Label ID="MessageLabel" runat="server"
                   Style="z-index: 100; left: 0px; position: relative;
                           top: 0px" Text="">
               </asp:Label>
           </td>
       </tr>          
   </tbody>
</table>

Contact.aspx.cs (* = omitted private info)
-----------------------------------------------------
// Create and Send E-mail based on user input
//
protected void SendFeedbackEmail(object sender, EventArgs e)
{
   const string DaveName = "Dave Hardenbrook",
                DaveAddy = "*****@*****.com";
   const string password = "*****************";

   try
   {
       SmtpClient smtpc =
           new SmtpClient("smtpout.secureserver.net", 80);

       MailMessage mmsg = new MailMessage();

       // Create E-mail address objects, sender and recipient (= Dave)
       //
       MailAddress FromAddy = new MailAddress(TB_EmailFrom.Text,
                                      TB_Name.Text);
       //
       MailAddress ToAddy = new MailAddress(DaveAddy, DaveName);

       // Set E-mail Message params
       //
       mmsg.From = FromAddy;
       mmsg.To.Add(ToAddy);
       mmsg.Subject = TB_EmailSubject.Text;
       mmsg.Body = TB_EmailBody.Text;

       // Set SMTP Credentials
       //
       smtpc.Credentials =
            new System.Net.NetworkCredential(DaveAddy, password);

       // Dispatch E-mail
       //
       smtpc.Send(mmsg);

       // Print result
       //
       MessageLabel.Text = "Sent!";
   }
   catch (Exception ex)
   {
       // Display Error
       //
       MessageLabel.Text = "Couldn't send E-mail: " + ex.Message;
   }
}