Thank you, kitz and havelock, for your time and trouble in replying and I apologise for the time it has taken me to get back.
I will try both your "fixes" and see what happens.
There is a twist in the tail, however, as I have today noticed that although I lost the blocked senders list, ( or so it appeared ), senders originally in the now empty list are still being correctly despatched to the deleted box.
So the names don't appear but they are being handled correctly................very odd.
I'm baffled, but that is nothing new.......