1password started doing this with fastmail, ux is not great as it's not easy to create one manually in 1p but only when you're autocompleting your email on a site, but I guess it will improve over time. https://1password.com/fastmail/

I use a catch all alias that maps all local parts to one account (unless a specific account or alias already exists)

Requires zero user action to make up an address

I do this but it requires 0 setup, it's a feature in Fastmail.

A catch-all that forwards to one account works very well.

Just a curl command with mailcow-dockerized

>Sounds tedious if it’s the former

Thankfully it isn't.

To set a catchall with sendmail, add a line to /etc/mail/virtusertable like so:

   @domain.tld <emailaddress>

And if I decide to block a particular address, which I've only had to do with addresses set up for specific sites (which I've then decided sends me too many emails -- I've yet to receive spam that's not from the site in question), add a line to /etc/mail/access like so:

   To:<specificsite>@domain.tld error:5.1.1:"550 User unknown"

And that can be temporarily (or permanently) reversed by commenting it out. I imagine it's something similar for postfix, qmail, exim, etc.

Edit: I'd add that I make extensive use of folders/filters to handle email as well, so unless I don't want to use a site/service any more, I'll usually create a filter unless I don't want any more contact with a specific entity -- then it's "user unknown" for that email address.