$re = '/^(?<local>[a-zA-Z0-9\.!#$%&\'*\-\/=?^_`{|}~"]+)(?:\.)?(?<routing>[a-zA-Z0-9\.!#$%&\'*\-\/=?^_`{|}~+"]*)(?:@)(?<domain>(?:[a-zA-Z0-9\-[\]]*)(?:\.)(?:[a-zA-Z0-9\-[\]\.]*))$/m';
$str = 'yemolai+hello+amps@gmail.com
romulogabriel@outlook.com.br
a13b3440.junior@gmail.jp
gabriel.rodrigues@sedop.pa.gov.br
rubens.junior00k@hotmail-p.com
adam.mills@[192.168.1.1]
a@B.com
';
preg_match_all($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