Where Should I Add That. <Add Key="Validationsettings:Unobtrusivevalidationmode" Value="None" />

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
  <connectionStrings>


        <add name="connString" connectionString="Data Source=INFND-DTP-0493;Initial Catalog=Test_DB; User ID=alok;Password=abcd@1234" providerName="System.Data.SqlClient" />



  </connectionStrings>
  <system.web>
    <compilation debug="true" targetFramework="4.5" />
    <httpRuntime targetFramework="4.5" />

  </system.web>
  <appSettings>

    <add key="SenderEmail" value="xyz.com" />
    <add key="SenderName" value="Admin" />
    <add key="RecipientEmail" value="xyz.com" />
    <add key="RecipientName" value=" Admin" />
    <add key="SmtpServer" value="mail.pqr.com" />
    <add key="SmtpServerUserName" value="webforms@abc.com" />
    <add key="SmtpServerPassword" value="web1234forms" />
    <add key="SmtpServerPort" value="25" />
    <add key="SmtpEnableSsl" value="false" />
    <add key="SmtpServerDefaultPort" value="25" />
    <add key="SmtpUseDefaultCredentials" value="false" />

  </appSettings>
</configuration>