Fastmail also has a catch all / wildcard option which I am using. You don't need to create aliases for every email; instead any email to *@mydomain.com goes to my single email inbox. And similarly I can send from [email protected].

I use a subdomain for it. Anything to that subdomain is marked as read and filed in the "spam-adjacent" folder. I'll look in there for transactional stuff and marketing bs never increments my unread counter. Only real people appear in my actual inbox and it's basically email nirvana.

The way I do it is I use a subdomain for any aliased email, e.g. [email protected] and then I just have rules to move anything sent to account.mydomain.com to a separate folder, then it never shows up in the main mailbox unless I put it there myself. Works fine!