I reset the App (All Settings / Apps / Apps and features / Mail and Calendar / Advanced options / Reset) a bit over 2 weeks ago. It seems to be better. However, sync problems with G Mail occurred again after a couple of days, but I deleted and re-installed G mail and it has worked OK since then. The only other issue was one time when I forwarded an Email. When I clicked “Forward” the text changed to one letter wide in a long descending column of single letters. However I selected the text and removed the formatting and that fixed it.
This how to remove formatting in Win 10 Mail App. First select the area (highlight) or Ctrl/A to select all and:
After the Reset, the App is working well enough. So, I will keep using the App rather than Outlook and post again if there are any more issues.
5th April. Issues with Gmail are continuing. Gmail stops syncing and the formatting issues seem to also be with Gmail. I give up.