The WordPress Restrict Email domains plugin allows you to 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)
This plugin is best suited for intranets, educational institutes or the cases when you do not want to allow registration from everyone but a subset of users based on their email address. If you want to limit registrations on your WordPress, BuddyPress, WooCommerce website to the emails belonging to only specified domains, this plugin is for you. It goes one step further and allows you to allow users by emails, or domains or even the domain extensions. So, if you are building an educational website and only want to allow the users from .edu domain, just put .edu in the settings. Same goes with the domain. If you are building a corporate network and only want to allow users from your own network, put your domain name in the settings.
It’s easy and efficient. The use of regular expression gives it a lot of flexibility. This plugin helps fight spam too.