$re = '/^(?!.*\.-.*$|.*-\..*$)([a-zA-Z0-9._-]+)([a-zA-Z0-9]@[a-zA-Z0-9])([a-zA-Z0-9.-]+)([a-zA-Z0-9]\.[a-zA-Z]{2,3})$/im';
$str = 'chris@data.services.com
chris@data-services.com
chris@data.-services.com';
preg_match_all($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