Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
    Try
        Dim SmtpServer As New SmtpClient()
        Dim mail As New MailMessage()
        SmtpServer.Credentials = New Net.NetworkCredential("xxxx@gmail.com", "xxxxx")
        SmtpServer.Port = 587
        SmtpServer.Host = "smtp.gmail.com"
        SmtpServer.EnableSsl = True
        mail = New MailMessage()
        mail.From = New MailAddress(TextBox2.Text, "Tourism")
        mail.ReplyTo = New MailAddress(TextBox2.Text)
        mail.To.Add("xxxx@gmail.com")
        mail.Subject = "UTTARAKHAND TOURISM : QUICK CONTACT QUERY"
        mail.Body = "<B>" + "||| -- UTTARAKHAND TOURISM : QUICK CONTACT QUERY -- |||" + "</B>" + "<BR><BR><BR>" + "<B>" + "Client Name : " + "</B>" & " " & TextBox1.Text + "<BR><BR>" + "<B>" + "Email : " + "</B>" & " " & TextBox2.Text + "<BR><BR>" + "<B>" + "Mobile No. : " + "</B>" & " " & TextBox3.Text + "<BR><BR>" + "<B>" + "City : " + "</B>" & " " & TextBox4.Text + "<BR><BR>" + "<B>" + "Country : " + "</B>" & " " & DropDownList1.SelectedItem.Text + "<BR><BR>" + "<B>" + "Query Regarding : " + "</B>" & " " & TextBox6.Text + "<BR><BR>" + "<B>" + "Query : " + "</B>" & " " & TextBox7.Text + "<BR><BR>"
        mail.IsBodyHtml = True
        SmtpServer.Send(mail)
        Label8.Visible = True

    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try
    TextBox1.Text = ""
    TextBox2.Text = ""
    TextBox2.Text = ""
    TextBox3.Text = ""
    TextBox4.Text = ""
    DropDownList1.SelectedItem.Text = "Select Country"
    TextBox6.Text = ""
    TextBox7.Text = ""
End Sub

Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
    Response.Redirect(Request.Url.AbsoluteUri)
End Sub
End Class

Server Error in '/' Application.