You can restrict registration for an event so that only people with an email address from specific email domains can sign up.
How to set it up
Go to `Settings`
Click on `Setup`
Enable `Require email verification to sign up`
Under Allowed email domains, enter the email domain you want to allow, for example @company.com
Click `Add`
Add additional email domains if you want to allow more than one.
Once an email domains have been added, only people with an email address from those domains can sign up.
If Allowed email domains is left empty, people with any email domain can sign up.