As others have said, you can set up aliases / groups and those do not require additional accounts.
Also if you’re the only account then you can just configure a catch-all in the routing section so that anything@your domain goes to you. That’s no additional cost even on these basic accounts I believe.
I use this so I can also track by using a new address for each service (e.g. twitter@mydomain.com, ebay@mydomain.com, etc)