ASP.NET

<customErrors mode="On" defaultRedirect="Error.aspx">
    <error statusCode="403" redirect="Error.aspx"/>
    <error statusCode="404" redirect="Error.aspx"/>
</customErrors>

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        Send_log();
    }
}

private void Send_log()
    {
           String Client_URL = GetCurrentPageName(); //This is used Because we needed to know where was the Exception comming from(Client)

            Exception objErr = Server.GetLastError();
         
            MailMessage mm = new MailMessage();

            SmtpClient smtp = new SmtpClient();

            mm.From = new MailAddress("vuyiswamb@gmail.com");

            mm.To.Add(new MailAddress("Vuyiswa@its.co.za"));

            // mm.To.Add(new MailAddress("abacussupport@its.co.za"));

            mm.Subject = "Exception Report from " + Client_URL + "In EXAM/CLASS";

            mm.Body = objErr.ToString();

            mm.IsBodyHtml = true;

            smtp.Host = "smtp.gmail.com";

            smtp.EnableSsl = true;

            System.Net.NetworkCredential NetworkCred = new System.Net.NetworkCredential();

            NetworkCred.UserName = "vuyiswamb@gmail.com";

            NetworkCred.Password = "wow";

            smtp.UseDefaultCredentials = true;

            smtp.Credentials = NetworkCred;

            smtp.Port = 587;

            smtp.Send(mm);
   }

Exception objErr = Server.GetLastError();

Response.Redirect("MissingPage.aspx"); 

...
SomeFunction();
...