I use a subdomain; making your main domain a catch-all will eventually result in a deluge of spam.

Instead of [everything]@example.com, I set up [everything]@yo.example.com. Discovering subdomains is much harder and the one time I encountered a form that didn't like a subdomain, I just made a forwarding address on my main domain.

Using Fastmail's rules, I have a setup where every message arriving to @yo.example.com gets shunted into a folder unless there's a different rule putting it somewhere else.

> Discovering subdomains is much harder...

Is this because you don’t publish MX records in DNS for the subdomains and the default setting on the main domain is to accept only specific addresses (and reject catch-all addresses)?

Personally I haven't been hit with spam to truly random addresses with my catchall. Is that a common issue people run into?

The spam I've received on my catchall is either based on previously breached sites (which I once signed up to) or to very common mailbox names (e.g. postmaster@, info@). I just add those to an auto-reject postfix filter based on the intended recipient, which keeps my inbox very clean.

Years ago I just set up some filters. There's only about 5-10 email addresses that get hammered with SPAM.

Gmail handles the rest.