Mail Continuously Crashes - Monterey 12.7.5

To close out this issue, I backed up everything via Time Machine - not as simple as it should have been as it would not recognise my NAS which had not previously been a problem. I then reformatted the hard drive and reinstalled the latest version of Monterey. (I did delay this quite a bit after my return from vacation, anticipating a lot of pain and grief, and used my Macbook instead).

Having the Time Machine backup, everything went quite smoothly (much to my surprise as I never succeeded in the past so I had done manual backups of all the important items including the Mail/V9 folder) and my computer was running as it should but quite a bit faster, in about 3 hours total with only a few verification passwords to be entered. Mail is stable as are connections to the outside world.

Given the success of this exercise, I will not be so reluctant to repeat it in the future should the computer slow down or have issues.

Many thanks to all those who have provided advice and support, especially BDAqua