title: How to protect from HTML <base> tag?
body: <p>Documentation about the tag says it must located inside of the <code>&lt;head&gt;</code> and only one <code>&lt;base&gt;</code> tag is permitted.</p>
  
  <p>However, this tag successfully replaces base URL for relative links even its been put somewhere inside the <code>&lt;body&gt;</code>.</p>
  
  <p>The behavior was noticed in a support ticket system with many relative links. The system renders emails, and if an email's HTML code contains the <code>&lt;base&gt;</code> tag, after the email is rendered, all relative links change to the base URL specified in the tag.</p>
  
  <p>The behavior confirmed for Firefox, Chromium-based browsers, Edge. IE11 ignores it. You can check a simple sample <a href="http://jsbin.com/jewakam" rel="nofollow noreferrer">here</a>.</p>
  
  <p>Is it possible to protect from such behavior without changing website's HTML markup?</p>