$re = '/USERS: ([^!]*[a-zA-Z]\d{3})![^@]+@[^ ]+ \([^) ]+\) \(\S+\) connected to the network /m';
$str = 'USERS: Stephanie800!Mibbit@xx.xx.xx.xx (555560E4.5124B86E.EB45475D.IP) (http://www.mibbit.com) connected to the network (our network is here)';
preg_match_all($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