How to change invitation letter for new user

Hi, forum,

I’m working on changing the invitation letter for a new user. I found a method in the documentation that allows you to change all letters. But I need only invitation letter.

The class responsible for sending out the invitation letter is located here. apps/settings/lib/Mailer/NewUserMailHelper.php. But it cannot be accessed from the configuration file config.php. Tell me, are there any ways to change the invitation letter without editing the sources? Or maybe there’s a way to attach documents to an invitation letter?