Thank you so much, Greg. My daughter-in-law forwarded your message to me after learning that I have had this same e-mail problem. I did send a comment to the Feedback Hub, including my case number and how the Microsoft employees had actually misdiagnosed the problem. Appreciate your comments!
I have experimented a little with this problem and although it doesn't address the issue regarding Windows Mail it had some surprising developments. I have four email accounts in the Windows Mail app but it was the Rocketmail (Yahoo) account where I first experienced the code. So I visited my account on the web and discovered the email was as it should be. I decided to forward this to my Gmail account and opened it in the Windows Mail app. Hey Presto!! The mail could be read as intended.
The question now was ... could it be Windows Mail causing the problem? I decided to uninstall the Windows Mail app, restart my PC and then reinstall the app. Of course, it also meant that I would need to go back and add each of my email accounts into Windows Mail. Having done this I forwarded the email from Gmail to Rocketmail and it worked, the email could be read So, where do I stand now? Is the Windows Mail app to blame? I leave that to the Microsoft team to fathom out!!