I also have my own mailserver and I don't create new accounts, I have a wildcard filter that drops all emails that come to my domain in my inbox. This is of course only viable when you are the only person using the domain, but I just sign up with a new mail address every time I sign up, for example my hackernews account would be [email protected] That way I have a clear differentiator for every domain.
I do something similar except that I do not allow wildcard reception - I create unique service-identifying user@ for each service I give an address to, and have a simple script that immediately adds that to the Postfix virtual table.
That way the SMTP server can reject all unknown user@ without accepting them in the first place - preventing spamming and some types of denial of service through resource starvation.
I also apply greylist based on a unique tuple (From, To, client IP address) so on first connection with that tuple valid SMTP clients need to re-deliver the email after a waiting period. Any subsequent delivers are accepted immediately.
That's a pretty cool approach! I'd only be worried about the risk of leaking the main account address when responding to anything, but it's probably doable with a bit of research, like Postfix catch-all setups seem straightforward enough.
FWIW that should just be a matter of using the right configuration and mail client. With Fastmail for example I get to use a catch-all setup with my domain, and respond to whatever email it was sent to.
And the other way around as well. Send an email from an arbitrary <whatever>@domain email address.
