title: Is "@" a special character in regular expressions?
body: <p>I am working on an email filter and I have come across a list of regular expressions that are used to block all emails coming from senders that match a record in that list. While browsing through the list, I have discovered that <em>all</em> occurrences of the <code>@</code> character are escaped with a <code>\</code>.</p>
  
  <p>Does the <code>@</code> mean anything special in regular expressions and needs to be escaped like so <code>\@</code>?</p>