Unable to send email in Visual Web Developer 2010 VB

Question

I am using Visual Web Developer 2010 and Visual Basic with NET version 4. I want to send an email from a web page I have Created. I have referenced System.Net from the Solution Explorer References page. The code runs without error but no email message is sent. Below is a copy of the code.

Imports System.Net.Mail

Protected Sub Button1_Click(sender As Object, e As System.EventArgs) Handles Button1.Click

        Dim mm As New System.Net.Mail.MailMessage("my email address", "recipients email address")

        mm.IsBodyHtml = True

        mm.Body = "<h1>Hello World</h1>"

        mm.Subject = "Test"

        Dim client As New System.Net.Mail.SmtpClient("Service provider smtp address")

        client.Credentials = New System.Net.NetworkCredential("my user name", "my password")

        client.Send(mm)

        Dispose()

    End Sub

Any help or suggestions would be greatly appreciated.

Many thanks

Steve