title: How to store cookie permanently
body: <p>I don't want to show mail id in my application code. I want to give text box and what ever email id I will give it should be stored in web.config file for ever until I change it.</p>
  
  <pre><code>string store= "kumar@gmail.com";
  ConfigurationManager.AppSettings["MailId"] = store;
  string message1 = ConfigurationManager.AppSettings["MailId"];
  
  &lt;appSettings&gt;
      &lt;add key="aspnet:MaxHttpCollectionKeys" value="2001"/&gt;
      &lt;add key="MailId" value="krishnamohan.p@sun.com" /&gt;
  &lt;/appSettings&gt;
  </code></pre>