So it looks like from this code that the $from_email (used also as the $to_email for admin emails) is being called from the database. So you need to look in the database. It is being read from a table called 'subscriptions_response', so access your database via your host, find the table, take a look at the emails in there.
Hope that helps,
Best wishes,
Paul.
PS Looking at the form from the first bit of code it might be calling a page on pages/subscribers which is either a method called subscribers in pages.php or more likely the index method in subscribers.php in a folder called pages.
PPS The homepage is defined in the config file and can be any controller in the root of the controllers folder. That controller can be calling any view, in any subfolder structure, so again, it is not possible to say if this is the code that you posted or if it is some old unused code that was left, and the actual code could be hidden away somewhere else. This all sounds far more complicated than it actually is, just impossible to say as I am in the dark. Anyway, good luck with it.
