Sudden increase in iCloud spam.

You need to follow the articles Report and reduce spam in iCloud Mail - Apple Support

Manage junk mail in Mail on iCloud.com - Apple Support

Me too, I wonder if Apple has changed the default spam filters. I don’t use my iCloud email address much except to use iCloud services but I have had the addresses since the very beginning.

Please don’t reply with the help article about spam, did it years ago.

This is new behavior.

Same. Hundreds of spam mail a day and I cannot get it to stop. I have tried unsubscribing but I get an error that it didn't come from a valid email address. I have marked them as JUNK so now that folder is going rampant. I have tried to block the sender but they just keep coming. I want to delete this email all together now because of it but you cannot get another iCloud email. The apple support chat guy told me to create a new third party email and make that my new Apple ID and just stop using my iCloud account. That isn't fixing the problem and why do I need another email address? Why can't I get a new iCloud email and update my Apple ID? Because Apple says no.