Setting Problem of Email Restriction for Blacklist

Hi,

We are using Gitlab CE with version 14.5.0 for git. For security issue, we would like to restrict people to register an account. We have added whitelisted domain, and we want to restrict only special pattern of email into a whitelist. But only blacklist is found in admin settings.

There is no example for how to apply the email restriction in Gitlab official website. Here is our cases. We would like to restrict the email containing special characters or digits. So, the pattern we used is like “^.[_-|\|/|*|+|0-9]+.@ourwhitelistdomain.com$” or “^.[_-|\|/|*|+|0-9]+.$”.

However, no matter what regex is applied to the blacklist is not working. Could anyone help us?
Thanks.

B.R.,
C.T.