pdate: MS has now installed Outlook again, minus my other email accounts. Mail no longer functions, along with my other email accounts
They have been warning they were going to do this for some time, albeit they have actioned it earlier than they said. Outlook doesn't want to know about my ISP email, despite the fact that Windows Mail had no trouble with it. I now have to access that account via a Webmail facility.
The Outlook email ads threat has not turned out to be as bad as expected - just a couple a day at the moment.