I’m looking into getting some domains for email, so I don’t need to use the same few addresses for everything.

Getting a custom domain for email is smart. It’s a necessary step given how data is treated these days. The domain becomes your identifier, but it's essentially arbitrary. I switched from sharing a single email address (which predictably led to breaches and spam) to creating dedicated emails for each service. Now, when an account gets compromised, I just redirect that email to oblivion. It’s a clean break, and a strangely revealing look at how online identities get resold and repurposed. Worth considering.

Use an email alias. Domains are not connected to you. Shared with thousands of other people.

Something you can remember...

Catch alls are most useful when you are away and you need to give an email out. If you can't remember the domain that becomes a pain.

I set up my postfix server so that anything after a hyphen ("-") becomes a wildcard. It like Gmail's "plus addressing", but the hyphen is more subtle. It means multiple users can make infinite aliases on one domain.

So, "user@domain.com" has the same mailbox as "user-somesuffix@domain.com".

Look into https://simplelogin.io/

They make creating random aliases for custom domains like this easy.

As for the domain name itself, anything that already looks like a mail service is good. “examplemail.com” or “mailexample.com”

I went to expireddomains.net and searched for ones ending in "__mail.net". Found a good, short domain that was once a regional ISP and email provider 15-20 years ago. (I still get spam for some of their old subscribers.).

I do not use subdomains for this one. Generally, I combine a simple name with a number for the mailbox name. Like "johnathan2715@zzzmail.net" if I think it needs to look like a real name, or some other word like "giraffe1238" or something like that.

It's working great.

I just use a single catch-all account in my existing domain. If you send an email to my primary address it just goes to my primary box. If you send an email to my secondary address it goes to my secondary box. If you send an email to anything else it goes to my catch-all box.

Rumba@mycustomdomain.com Skips the catch only goes right to me.

Intel@mycustomdomain.com Go straight to the catch-all

I don't have to pre-make them I simply use anything that doesn't exist.

All of me and my family's domains have a subdomain for signing up to stuff. They all have a catchall and we just signup with service.tld@subdomain.example.com. Anything that gets misused gets blocked.