[jimktrains2]

Each family member has a subdomain all to themselves. The website before the @ allows them to know where the sender got the email address from. You can have catch-all addresses on emails, so anything without a mailbox is sent to the default mailbox that's configured.

It need not be self hosted to do this. Most email providers provide this functionality.

[jszymborski]

That's exactly right. I don't self-host the email (you can use any service that takes catch-alls like mailbox.org).

anything '@subdomain' gets forwarded to its respective family member's email.