Only allow one specific email domain

I want to only allow emails from our company be able to sign up for internet access. How do I accomplish this?

Please elaborate how you are doing it on the moment to give acces to the Internet?

We are using User Manager with the option to click a link and signup (All OOTB soulutions). I want to limit that signup to only one(1) domain.

Userman is new to me and I can’t use the demo page userman.mt.lv so I looked in the Wiki and forum and you can use prefix but then the domain is at the back of the string so that is not going to fly.

The only thing is then to look if a Radius sever will work for you.

If any one else knows a better reply please let it know!