title: What is and why is my email client trying to use opencounter in a bulk email?
body: <p>We found some code being inserted into emails sent by our proprietary email system and have no idea of its provenance.</p>
  
  <p>My company sends a lot of bulk email for clients.  (We follow all the best practice protocols to ensure we're not spammers.) The system is proprietary, based on open source code.  Customers have a GUI to enter content, similar to the big guys like MailChimp and the like.</p>
  
  <p>A staff member brought a UI challenge with the GUI to me, using a client's bulk email as an example.  I dug into the source to see if they had some exotic CSS that might be affecting my interface, when I noticed the following tag:</p>
  
  <pre><code>&lt;custom name="opencounter" type="tracking"&gt; &lt;/custom&gt;
  </code></pre>
  
  <p>My interface certainly doesn't insert that code into an email.</p>
  
  <p>What is opencounter?  Who's technology is it?  Does it have a valid reason for being used on our (proprietary) email system?</p>