Spam has increased enormously over the last months. How to stop it?

First, I'm using two Macs with Sonoma 14.0 as well as two iPads and an iPhone 14 with latest iOS. Apple Email is totally up-to-date on all these devices.

Over the last months I've seen an incredible increase in spam being sent to my two iCloud email address, one of them is an alias both are on the same iCloud account. For many years I've used these addresses and had pretty much no spam. Then some months ago this spam started on both emails and it has been increasing steadily.

The vast majority of it goes to my Junk mailbox but always there are a few real emails that go into the Junk mailbox so having that Junk mailbox is kind of useless as I have to go through all the spam to check there aren't any real emails.

The most amazing thing about the spam is that one of the two emails I have used only for my family, there are five people with that email address and it has never been used in web-site, forum or anything. Yet still it is attracting a load of spam. The other email address I use for communicating with businesses and suchlike.

I do have a handful of Gmail addresses which I have always used for online discussion forums and that kind of thing, and yet there is hardly any spam for them. I've had those for many years and I have never been very cautious about spam with those because I can easily just replace them with a new one if it gets too much spam. Anyway those Gmail addresses are relatively spam free whereas my two iCloud email addresses which I am extremely careful with both now have loads of spam every day.

Okay so now I want ask an actual question. Is there any way to reduce this spam?

I have been applying "Block Contact" to the emails in the Junk mailbox but this makes no difference. I guess that "Block Contact" just sends emails to the Junk mailbox. What I want is some way to completely stop emails with certain email address from coming to me at all.

Have I understood "Block Contact" correctly?

Is there a third party utility for controlling spam?

Is there any other way to do this that I have not considered?

I have to say that now I am contemplating just stopping using iCloud mail altogether and instead changing to Gmail.

Thank you for any assistance you can give.

Patrick