Problém - v subjectu e-mailu se vymaže mezera

v souboru /web/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/AbstractHeader.php
upravit 

:
//foreach (preg_split('~(?=[\t ])~', $string ?? '') as $token) {

foreach (preg_split('~(?<=[\t ])~', $string) as $token) { // regexp