my Booking Form This Show Server Error in Application.

Plz Help Urgent

web site link http://www.dehraduntaxihire.com/

It is showing me following error on the page

C# Page Code

using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Data.SqlClient;

using System.Text;

using System.IO;

public partial class inquiry : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void sbt_Click(object sender, EventArgs e)

{

StringBuilder mailcontent2 = new StringBuilder("

Query | Dehradun Taxi Hire");

mailcontent2.Append(

"");        mailcontent2.Append("
");        mailcontent2.Append("
");        mailcontent2.Append("
");        mailcontent2.Append("
Name    " + txt1.Text + "   
Period   From  " + TextBox1.Text + "  
Phone    " + TextBox2.Text + "   
Message    " + TextBox3.Text + "   
 
 ");

System.Net.Mail.MailMessage mailMessage2 = new System.Net.Mail.MailMessage(TextBox1.Text, "[email protected]");

mailMessage2.Body = Convert.ToString(mailcontent2);

mailMessage2.Subject = "Dehradun Taxi Hire - Inquiry";

mailMessage2.IsBodyHtml = true;

System.Net.Mail.SmtpClient mailClient3 = new System.Net.Mail.SmtpClient();

        System.Net.NetworkCredential basicAuthenticationInfo2 = new System.Net.NetworkCredential("[email protected]", "i(Zzx%IdK{5");

mailClient3.Host = "216.224.185.13";

mailClient3.UseDefaultCredentials = false;

mailClient3.Credentials = basicAuthenticationInfo2;

mailClient3.Send(mailMessage2);

string strScript = "alert('Thank you for your inquiry; we will get back to you within 12 hours.');";

Page.ClientScript.RegisterStartupScript(this.GetType(), "alertBox", strScript, true);

}

Aspx Page Code

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="inquiry.aspx.cs" Inherits="inquiry" %>

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

<title>title>

head>

<body>

<form id="form1" runat="server">

<asp:TextBox ID="txt1" runat="server" CssClass="form-control" placeholder="Name">asp:TextBox><br/>

<asp:TextBox ID="TextBox1" runat="server" CssClass="form-control" placeholder="E-mail">asp:TextBox><br/>

<asp:TextBox ID="TextBox2" runat="server" CssClass="form-control" placeholder="Phone">asp:TextBox><br/>

         <asp:TextBox ID="TextBox3" runat="server" CssClass="form-control" placeholder="Your Message" TextMode="MultiLine">asp:TextBox><br/>

<asp:Button ID="sbt" runat="server" Text="SUBMIT" OnClick="sbt_Click" />

form>

body>

html>

Html Page

<span style=""background-color:" #ff0000;"=""><strong><script type="text/javascript">

var iframesrc1="inquiry.aspx"

document.write('<iframe id="test" src="'+iframesrc1+'" width="280px" height="150px" border="0px" marginwidth="0" marginheight="0" hspace="0" vspace="0" frameborder="0" scrolling="no">iframe>')

script>