And a nod to trying UBLOCK ORIGIN but that won't block the emails but does make Yahoo more bearable.
I probably went about dealing with this in the wrong manner by awarding the “This answered my question” first then trying to submit my answer. I keep getting a notice that I can’t post my answer and to try again now or later. I am entering this Answer as a new question, please forgive me for any inconvenience or confusion.
Thanks for coming to my aid, yet again!
Your explanation makes sense about the spammers paying to not have their ads blocked. But this is a travesty of the “Block” facility offered by the mail provider, in my case, Yahoo. The old adage of “Money Talks” seems to ring true!
The thought of the work involved in transferring my store of emails from their respective folders, and to which I refer to from time to time, to a new provider - ? Thunderbird or whatever- is somewhat daunting, and in reality not really a viable option, having been building up for the last 15 or so years!
I shall probably “soldier on” in my present state. The only ‘consolation’ being that a great many of them actually now end up in my Spam Folder since trying to block them, but as I mentioned, some do not!
So, a “Best Answer” or “This Answered My Question” award to you, and here’s to the next time!