title: Codeigniter custom email validation rules
body: <p>Can someone please provide some advise on how to go about creating custom validation rules for Codeigniter.</p>
  
  <p>The website I am working on is for university students and only allows users to register if they use their university email address.</p>
  
  <p>Here is an example of the type of validation I am trying to achieve:</p>
  
  <p>Only allow emails that end with:</p>
  
  <pre><code>array(
      '0' =&gt; '@uni-email-1.com',
      '1' =&gt; '@uni-email-2.com',
      '2' =&gt; '@uni-email-3.com',
      '3' =&gt; '@uni-email-4.com',
  );
  </code></pre>
  
  <p>I am still quite new to codeigniter and I am not sure how to create this type of validation.</p>
  
  <p>Any assistance is very much appreciated!</p>
  
  <p>Thanks</p>