Spinning wheel in Macmail

I am operating Big Sur 11.6.7

I will explain step by step what I have done

• I accidentally deleted a folder - containing many subfolders and e-mails in my Macmail
• Looked everywhere but could not find it - thought I might find it in libraries but was not sure what to look at
• rang APPLE CARE and after over an hour of checking - I gave him access to my screen, i suggested we do restore from my backup back onto my same USER to an earlier time which I knew was there
• Restored Ok and file missing file was there - hooray
• Now - every time I open Macmail, I get a spinning wheel again which affects the operation of any program I get - so obviously Macmail is still the problem
• rang APPLECARE again and they suggested I re-install BigSur so it would give me the latest updates
• I did a complete install of Big Sur - rebooted and had another look
• STILL THE SAME
• I decided to turn off macmail and computer runs WELL - NO SPINNING WHEEL!
• I know there is something wrong with my Macmail because when I had it on, my e-mails on my Iphone did not sync - using IMap as they used to
• I am writing to the communities because to be honest I don't think APPLE Care rep looked at it deep enough to fix fault and I have had good results from the communities in the past
• i am happy to use ETRECHECK so you can have a look at the proble.
• THANK YOU FOR LISTENING