The page isn't redirecting properly while redirecting to custom error page

Question

while entering any page which is not exist. its giving error - The page isn't redirecting properly .its not redirecting to HttperrorPage.aspx

is this code correct ? will it go custom error page or it will send mail.

void Application_Error(object sender, EventArgs e) 
{
    Exception ex = Server.GetLastError();
    if (ex.GetType() == typeof(HttpException))
    {
        if (ex.Message.Contains("NoCatch") || ex.Message.Contains("maxUrlLength"))
            return;

        Response.Redirect("HttpErrorPage.aspx");

    }
    Response.Write("<h1 style='text-align:center'>Sorry There is Some Technical Problems Occured.Try again Later </h2>\n");
    Response.Write("<h1 style='text-align:center'>We Will get back to u shortly</h2>\n");
    EmailTheException(ex);
    Server.ClearError();
}
private void EmailTheException(Exception ex)
{
    System.Net.Mail.MailMessage mail = new System.Net.Mail.MailMessage();
    mail.To.Add(new System.Net.Mail.MailAddress("[email protected]"));
    mail.Subject = "An Application Exception has Occurred.";
    mail.Body = ex.ToString();

    System.Net.Mail.SmtpClient MailServer = new System.Net.Mail.SmtpClient();
    try
    {
       // MailServer.Send(mail);
    }
    catch (System.Net.Mail.SmtpException smtpEx)
    {
        //write logging code here and capture smtpEx.Message
    }
}

Answer 1

Will relative path works? Response.Redirect("~/HttpErrorPage.aspx");