Hello,
Prestashop 1.7.7.2.
I'm trying to remove the shop name prefix from emails subject.
Sounds quite easy, therefore I just comment out below line ./classes/Mail.php:
$subject = '[' . strip_tags($configuration['PS_SHOP_NAME']) . '] ' . $subject;
But...here magic appears. I changed the status of a test order to force mail notification, keeping my fingers crossed but I received email with added prefix! 
I have forced recompilation, cache is OFF, all changes are immediately visible.
I've moved one step forward and I also comment out:
$message->setSubject($subject);
and it works like a charm - I received email without subject.
Seems, that Mail::Send function is somewhere invoked with shop name prefix added (subject argument)
public static function send(
$idLang,
$template,
$subject,
$templateVars,
$to,
$toName = null,
$from = null,
$fromName = null,
$fileAttachment = null,
$mode_smtp = null,
$templatePath = _PS_MAIL_DIR_,
$die = false,
$idShop = null,
$bcc = null,
$replyTo = null,
$replyToName = null
)
Does anyone have an idea, what's going on?
I'm an software engineer, but experienced with embedded systems rather than web development - and this is my first attempt to setup the shop.
Regards!
BTW: If this may help. I changed the shop name yesterday. Displayed name in email is correct (new shop name) but the email subject contains old shop name, what is also strange.