title: I want to modify this regex to include apostrophe
body: <p>This regex is used for validating email addresses, however it doesn't include the case for apostrophy (') which is a valid character in the first part of an email address.
  I have tried myself and to use some examples I found, but they don't work.  </p>
  
  <pre><code>^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$
  </code></pre>
  
  <p>How do I modify it slightly to support the ' character (apostraphy)?</p>