apple mail rules not working

I'll try to be brief. Some years ago when it was still allowed, I set up a secondary email address (xxxxx@icloud.com). Over the last six months or so spam to that address has increased and then doubled and tripled. One day there were 78 spam emails between 9am and noon. So I went to look at the email online thinking I could delete that address, except it wasn't anywhere to be found. I called support.

A helpful support person explained that the xxx@icloud.com addresses had been discontinued a good while ago. But, she explained, email addressed to my no-longer-existant email address would still be sent through to my primary email. As if it were an escape hatch.

Why? She couldn't tell me. Could that no-longer-existant email address be deleted? No.

So in theory, a thousand spam emails come addressed to the no-longer-existant email address every day, and they are fed directly into my main address? Yes, she said. That's the case. (I didn't ask why I never received notification that the no-longer-existant email address no longer existed.) First thing, I changed the no-longer-existant email address to the functioning one everywhere on line.

Then I sat down to write an Apple Mail rule. If 'any recipient' contained any part of the no-longer-existant email address, it was to go straight to the trash. I wrote the rule in several stages, the full address and then the address broken down.

At first this seemed to have worked, but now those emails addressed to the no-longer-existant email address have started popping up again.

It feels a little bit like a haunting. What can I do to fix this?

Any help much appreciated.