Help with Regex for setting new users to external (self-hosted)

Hello. I wonder if someone can help me with the regex expression when enabling " Set a new user to external" as described here (we have a self-hosted gitlab)

In our organisation with have email address with different subdomains; for example and and . How can I add a domain wildcard as regex so that Gitlab will treat all users with * as internel? Should it be \@*.domain\.com$

Thanks for any help.