One of the many advantages of using a hosted solution with your own domain is that you can receive email from arbitrary addresses in the same inbox. For example

One of the many advantages of using a hosted solution with your own domain is that you can receive email from arbitrary addresses in the same inbox. For example merchant1@inboxname.mydomain.com gets sent to my inbox at Fastmail. inboxname@mydomain.com doesn't exist, so there's no way to get my "real" email address from what I give out to merchants. If I start getting spam on an address, whoops, you and everyone you sold my email to get sent to a black hole in the cloud.