$re = '/([\p{L}.\'-+]+@(?:[a-z0-9.\-\p{L}]+.)+(?:[a-zA-Z0-9-\p{L}]{2,24}))/ui';
$str = '<p>Тест@домен.ком</p>
Тест@домен.ком
test@domain.com
γλώσσα@τομέας.com
<p>моят-тестов@пример.bg</p>';
preg_match_all($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