Postfix can support per-domain outgoing IP addresses - where do I change this?

I get this message when I do a system check, but I can’t find where to change it - using search doesn’t bring up any matches?

“Postfix can support per-domain outgoing IP addresses, but is not currently configured to do so. This can be setup in the Postfix Mailserver module.”

Found the answer here…

https://www.virtualmin.com/documentation/email/dependent