title: How to remove duplicate line by perl or bash?
body: <p>I have a list:</p>
  
  <pre><code>asd@domain.com
  fff@domain.com
  yyy@domain.com
  ttt@test.com
  rrr@test.com
  fff@test.com
  yyy@my.com
  yyy@my.com
  </code></pre>
  
  <p>How it possible to do this:</p>
  
  <p>if in whole list we see three or more email with same domain - all duplicates except first one need to remove.</p>
  
  <pre><code>Output:
  
  asd@domain.com
  ttt@test.com
  yyy@my.com
  yyy@my.com
  </code></pre>