This task requires you to install Newsletter extension.
We are not using the default view code (probably in viewExecute() in SpecialNewsletter.php as we are rendering this page directly from content/NewsletterContent.php.
The task will require also to remove any unwanted functions to interact with database as well (like taking in data from the db to show up in Special:Newsletter/id). We are currently taking this from the ContentHandler data, and not from db.
Mentor: @01tonythomas