$re = '/[&?]((?:firstName|lastName|phone1|address|zipcode)=|email=(?:.*@.*\.)?)[^&]*/';
$str = 'https://example.com/?&iframeLoad=true&firstName=David&lastName=Faber&email=xyzzy?@xyzzy.com&phone1=1234567890&address=myaddress&zipcode=myzip&isAvailableReferral=true&isAvailableDirect=false';
preg_match_all($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