Set OnUpdated-handler
<asp:SqlDataSource
...
UpdateCommand="..."
OnUpdated="OnDSUpdatedHandler">
</asp:SqlDataSource>
and use it to send email
<script runat="server">
private void OnDSUpdatedHandler(Object source, SqlDataSourceStatusEventArgs e) {
if (e.AffectedRows > 0) {
MailMessage mailMessage = new MailMessage();
...
SmtpClient smtpClient = new SmtpClient("smtp.your-isp.com");
smtpClient.Send(mailMessage);
}
}
</script>