I like the UI of 33mail more. It’s easier to click a link at the top of an email in w/e client you’re using vs digging through apple’s portal and ever changing menus to toggle the right thing off.
Unless it’s gotten easier in iOS15… right now on my iPhone it’s not possible to turn off forwarding.
I need to go to appleid.apple.com,
login, 2FA,
find the menu,
wait for it to load (bec it always seems to take like 5 seconds, even if I just opened it),
figure out which service is the one attached to the email I chose (names of company that makes the app and is thus associated with that ID may not always align with the name I know it as),
turn it off.
Also I don’t get to choose the email address, instead apple makes it a random mix of letters and numbers: which means I must save it to a password manager and hope I never need to manually type it in for some reason (say on a public PC).
With 33mail, the link to disable forwarding is in the header, like any unsubscribe link. You can still manage everything from their portal. You choose the domain and then they set it up as a catch all, to receive everything, except that which you say to deny. So you can have creative names for each service.