title: how could I combine these regex rules?
body: <p>I'm detecting @replies in a Twitter stream with the following PHP code using regexes.</p>
  
  <pre><code>$text = preg_replace('!^@([A-Za-z0-9_]+)!', '&lt;a href="http://twitter.com/$1" target="_blank"&gt;@$1&lt;/a&gt;', $text);
  $text = preg_replace('! @([A-Za-z0-9_]+)!', ' &lt;a href="http://twitter.com/$1" target="_blank"&gt;@$1&lt;/a&gt;', $text);
  </code></pre>
  
  <p>How can I best combine these two rules without false flagging email@domain.com as a reply?</p>