[SOLVED] (Postfix/dovecot) Is there a way to setup so every email going to a domain goes to same mailbox

Basically I want to create a subdomain like blackhole.example.com and I want any mail going to that domain, regardless of user, to go in the same mailbox. I need this for a test environment where I rewrite all the email addresses in a database to one that is local so the emails will be something like user.yahoo.com@blackhole.example.com

Idea being, I won't be accidentally sending out mail to real users when in the test environment. And I need to actually send mail to test certain things like password resets etc.

I can't for the life of me find much info online on how to do this, if it's even possible.

I thought it was maybe by using a wildcard in the /etc/postfix/virtual file but that did not work.