BOAC, thanks for the pointer, I didn't think to Google as Eudora has been stable for as long as we have had it, it has never caused concern before.
It transpires that Eudora has done some recent backups for us, on the 20 Dec and, earlier today, so I have restored to the 20 Dec state which gets her out of the major hole, work wise.
I note that the advise on one of the websites is to migrate away from Eudora. Eudora, themselves suggest keeping the inbox, Outbox and trashboxes all less than 1 MegaByte! Quite often the daily mail receipts can exceed 1 MegaByte, perhaps we need to get a different mail browser!
Thanks again,
Rans6....