Brilliant! Totally brilliant. Yep, that is exactly what I must have done. Pulled the divider back up and all is normal. So very grateful for your help. Many, many thanks. Always so simple when you know how!!
Richard
I was clearing out Mailboxes of unwanted files yesterday,moving the cursor around the screen to move down through a Mailbox, and the familiar appearance of the Mail Inbox/Sent/Trash/Mailboxes etc suddenly altered without my having touched the Preferences or deliberately altered any of the...