Dashing now, but as in the change of title post:
At the moment I turned off Adblocker, the problem went away. Not put to a proper test yet, but it does tally with your link.
I spoke to a high level of tech support at the Mail provider, and astonishingly she was unaware of it, despite some posts going back years!
She said they would work on it at the highest levels, so maybe I've done some good, or maybe she'll go to lunch and forget it.
The first level of 'support' said it was with their servers, but I'd already told him another computer was sorting normally. It was about then he bumped me up the the brains department.
