title: Html emails <hr/> styling issue
body: <p>I have a problem with e-mail clients reverting my styled <code>&lt;hr/&gt;</code> to one with just a solid line.</p>
  
  <p>The following is my mark-up, looks fine in Chrome and IE but Outlook always reverts the dotted line to a solid one.</p>
  
  <pre><code>&lt;hr style="background:none; border:dotted 1px #999999; border-width:1px 0 0 0; height:0; width:100%; margin:0px 0px 0px 0px; padding-top:10px;padding-bottom:10px;" &gt;&lt;/hr&gt;
  </code></pre>
  
  <p>I have looked at Campaign Monitor but nothing particular to guide me there.</p>
  
  <p>All answers appreciated.</p>