$re = '/(([^<>()\[\]\.,;:\s@\"]+(\.[^<>()\[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()\.,;\s@\"]+\.{0,1})+([^<>()\.,;:\s@\"]{2,}|[\d\.]+))/';
$str = '- VALID MAILS
Abc@example.com
Abc@example.com.
Abc@10.42.0.1
user@localserver
Abc.123@example.com
user+mailbox/department=shipping@example.com
"very.(),:;<>[]\\".VERY.\\"very@\\\\ \\"very\\".unusual"@strange.example.com
!#$%&\'*+-/=?^_`.{|}~@example.com
"()<>[]:,;@\\\\\\"!#$%&\'-/=?^_`{}| ~.a"@example.org
"Abc@def"@example.com
"Fred Bloggs"@example.com
"Joe.\\\\Blow"@example.com
Loïc.Accentué@voilà.fr
" "@example.org
user@[IPv6:2001:DB8::1]
- INVALID MAILS
Abc.example.com
A@b@c@example.com
a"b(c)d,e:f;g<h>i[j\\k]l@example.com
just"not"right@example.com
this is"not\\allowed@example.com
this\\ still\\"not\\\\allowed@example.com
john..doe@example.com
john.doe@example..com';
preg_match_all($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