$re = '`([A-z]{2}).*?(\d\d\W\d\d\W\d{2,4})\s*(.*)`m';
$str = 'SI12.08.2020 invoice already posted - status is incorrect - ticket at JIRA started 21.08.20
';
preg_match_all($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