Do you get so much spam from a specific email that you feel safe to ban it completely? Are you able to sue them or just send a strongly worded email about how they sold your email?
I also do this. There are some bad sellers that keep my email address and create a new email list for every promotion, so the Unsubscribe link in their emails always says something like “Unsubscribed from Promotion-2024-October” instead of “Unsubscribed from AnnoyingSeller”. Those get sinkholed.
I also once helped a seller discover that their contractor had stolen and resold their customer contact list when I started getting unrelated spam at that address and complained lol
Honestly, using a username generator in Bitwarden, it's so easy to do this that it basically "pays" for itself the first time you get a "true" spam email and it's effortless to identify who sold you out. I originally tried doing this manually but that was too much effort; now it's as simple and natural as generating a password for a new login. I see no reason to ever stop.
Of course, the vast majority of spam I get is marketing emails from companies I've actually done business with. Few if any even have an opt-in checkbox on their checkout form and those that do hardly ever honor it. There's simply nothing to be done about that except unsubscribe after the first time they spam you - and this is where having unique emails also helps, because those "unsubscribe" links are obviously riddled with tracking as well.
I do the exact same thing and I don't live in the US so suing a party that sells my shit isn't an option, but it's nice to be able to blackhole an alias so that the corporation in question doesn't get to bother me with their bullshit. It's only happened once or twice.
Now I know where the spam (I get) comes from.
I haven't had to ban any addresses yet.