Internal-only distribution alias?

I have a virtualmin server which is being used to host multiple domains for Postfix and Dovecot.

I have had a request for a mail alias (or email account) that sends mail to most of the addresses in its domain but that can only be emailed to by that same group (or another list, which would contain that same group). (Think of the “all-staff@your-company.com” that your managers use to tell everyone how exciting everything always is.)

I am certain that this can be done by some high wire act of rules or me tiptoeing around postfix config files, but I didn’t want to reinvent the wheel if there’s somewhere in virtualmin that just does that and I’m just not seeing it.

Thanks.

SYSTEM INFORMATION
OS type and version Ubuntu 24.04.4
Virtualmin version 8.1.0 GPL