The WordPress Restrict Email Domains plugin lets you limit/restrict user registration on your WordPress/ BuddyPress site by email domains. You can limit the registration by specific emails or domains or just the domain extensions (like .edu/.com)
You can limit user registration by email domains for:
WordPress
WordPress Multisite
BuddyBoss
BuddyPress
WooCommerce
Paid Memberships Pro
WP-Members
UsersWP
Ultimate Member
Allows you to limit new user registrations by:
Domain names (e.g example.com)
Extensions (e.g. .edu, will only allow emails having .edu domain)
Email addresses (e.g admin@you-website.com, friends@some-other-website.com)