sto provando il seguente script per l'invio di email:

<%@page language="VB" %>
<%@Import Namespace="System.Web.Util" %>

<script language="VB" runat="server">
Sub inviaEmail(Obj As Object, E As EventArgs)
'Creo l'oggetto MailMessage
Dim mailObj AS new MailMessage

'Setto i vari parametri
mailObj.From = "emailfrom"
mailObj.To = "emailto"
mailObj.Subject = "prova"
mailObj.Body = "ciao"

'Formato HTML della email
mailObj.BodyFormat = MailFormat.Html

'Invio la mail
SmtpMail.Send(mailObj)
End Sub
</script>

però mi dà il seguente errore:


Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: BC30002: Type 'MailMessage' is not defined.

Source Error:



Line 5: Sub inviaEmail(Obj As Object, E As EventArgs)
Line 6: 'Creo l'oggetto MailMessage
Line 7: Dim mailObj AS new MailMessage
Line 8:
Line 9: 'Setto i vari parametri


Source File: c:\inetpub\wwwroot\inviomail.aspx Line: 7

mi sapreste dire perchè?
grazie