title: Sort list in C# to merge the items of each list
body: <p>I have a list of emails grouped by hostname. I need to join these emails in an interleaved way and then send them.</p>
  <pre><code>public List&lt;string&gt; ReturnOrder()
  { 
      List&lt;string&gt; listMerge = new List&lt;string&gt;();
      List&lt;List&lt;string&gt;&gt; listEmail = new List&lt;List&lt;string&gt;&gt;();
      listEmail.Add(new List&lt;string&gt; { &quot;email01@yahoo.com&quot;, &quot;email02@yahoo.com&quot;, &quot;email03@yahoo.com&quot; });            
      listEmail.Add(new List&lt;string&gt; { &quot;email01@gmail.com&quot;, &quot;email02@gmail.com&quot; });
      listEmail.Add(new List&lt;string&gt; { &quot;email01@outlook.com&quot;, &quot;email02@outlook.com&quot;, &quot;email03@outlook.com&quot;, &quot;email04@outlook.com&quot;});
      return listMerge;
  }
  </code></pre>
  <pre>
  //Order:
  email01@yahoo.com
  email01@gmail.com
  email01@outlook.com
  email02@yahoo.com
  email02@gmail.com
  email02@outlook.com
  email03@yahoo.com
  email03@outlook.com
  email04@outlook.com
  </pre>
  <p>I need to get the following result, I made several unsuccessful attempts</p>