I'm doing the exact same thing. Built a small web app that lets me manage all my email aliases for the domain. Unfortunately there are a couple of websites that do only allow a select list of whitelisted domains meaning I cannot use my own, but for the other 99% it works wonders.
I wish I had had this idea ten years ago, it would have saved me so many headaches.
The most recent incident I remember was with a debrid service. I opened a ticket with their support and was told that the point of the policy was to combat abuse of their service. Not entirely sure why a paid service that accepts cryptocurrencies would care about email addresses.
Not as of right now, but I could put it on GitHub. It's essentially just a front end for the Gandi.net email management API. Manually editing the alias list gets cumbersome really quickly.
