iCloud email addresses

I have a mac.com email, which also gives me a johnny.appleseed@icloud.com email address.

However I also get spam email to jappleseed@icloud.com address. I never use this address and would be happy to kill it and all the spam that goes with it (some of which appears to come from a very prominent politician in the US).

I don't know how this address was created, whether by bot or human, although I suspect it was intentional because some of the messages start Dear [Not my name]. The address does not appear in my Apple ID details.

Any ideas?