In the same Main.php file we can extend the init() function to add a skin for mail
First define the new folder name as a constant
Code:
const <MAIL_SKIN_DIR = 'myMailSkin';
then add this line below the line that initializes the main skin dir.
Code:
\XLite\Core\Layout::getInstance()->addSkin(static::CUSTOMER_SKIN_DIR, \XLite::CUSTOMER_INTERFACE);
//New Line
\XLite\Core\Layout::getInstance()->addSkin(static::MAIL_SKIN_DIR, \XLite::MAIL_INTERFACE);
There are other skins you can alter!