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/