$re = '/rdstation(?!.*(email|inbound))/';
$str = 'utmcsr=rdstation|utmccn=curso-intro-coaching|utmcmd=inbound|utmctr=link3
utmcsr=rdstation|utmccn=agenda-psc|utmcmd=email
utmcsr=rdstation|utmccn=pnl-porto-alegre';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php