title: Regex to validate email format or some template string
body: <p>I have an email address field which is supposed to accept either an email address or a template string like this. <code>{TemplateString&lt;NUMBER&gt;}</code></p>
  <p>Required validations</p>
  <ol>
  <li>Either an email format <code>^\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b$</code> this is fine don't get carried away too much here :|</li>
  <li>OR the template format like <code>{TemplateString&lt;NUMBER&gt;}</code>
  <ol>
  <li>Start with <code>{</code></li>
  <li>Ends with <code>}</code></li>
  <li>The character(s) before the ending <code>}</code> should be a number</li>
  </ol>
  </li>
  </ol>
  <p>Example</p>
  <p><code>{HelloThere5}</code>, <code>{HowAreYou86}</code>, <code>{notcasesensitive9887}</code> are valid and <code>{ThisIsInVal88d}</code> is not.</p>
  <p>Thanks for the help</p>