[Normille]

Aye. But then, every time you want to create a new address, you have to go into your email admin/preferences/whatever and add that new email address as another alias. It soon ends up being a lot of work, so the tendency is [or was when I foolishly tried it] to just tick the "catch-all" box –with spam avalanche results.

[Someone]

That could be automated, and would make things as easy as what the OP described (could be as easy as “when I enter a new “from” address, add it to the list”)

[Normille]

Automation would definitely make the process less painful. I'm struggling to see how it could be done though, unless you're running your own mailserver.

I use Google email servers[0] [or 'Gsuite' as it's now called] to handle email for some of my domains and Yandex email for domains [1] [or 'Connect' as it's now called] for others. In order to create a new email account, or add a new alias, it involves logging in and clicking through a few screens of admin section. I'm not saying it couldn't be automated but I don't think it would be easy.

If anyone has done something like this, please share some tips!

[0] https://gsuite.google.com/ [1] https://connect.yandex.com/