BuddyPress: Allow only one email domain to register

In the BuddyPress, I want to allow register and log in using only one email domain. For instance, [email protected] restore all will be disallowed.

I have checked in the BuddyPress source and found that BuddyPress is using bp_core_validate_user_signup( $user_name, $user_email ) for sign up that has a filter

So I have tried to use the filter to modify the user_email filed as in the code below. But it is not working.

Question:

How can I validate email so it allows to register and login only from
one specific email domain?