Description:
------------
---
From manual page: http://www.php.net/filter.examples.validation
---
If we want to check email address like "11111/xxxx@yyyy.ru" - it's will be true. From 5.6 to 7.1

Test script:
---------------
if (filter_var('11111/xxxx@yyyy.zz', FILTER_VALIDATE_EMAIL)) {
    echo 'true';
}