Welcome back to Vista Forums dmillar337. You are still keeping a Vista system online and using Windows Mail to open emails in January 2020? That is probably not a very good idea from a security standpoint, but I am also quite attached to Vista. I believe we had a thread about your issue last year. Please look at the screenshot in this post and see if it looks familiar. Unfortunately, that thread was long on discussion but short on solutions.
Windows Mail uses Internet Explorer's engine. Even if you have Internet Explorer 9 updated to the time when Microsoft officially ended support for Vista, you have a very old browser engine that does not support TLS 1.2. I believe that is the cause of your "box with red x" issue. For average users, the best solution to almost every problem is to buy a Windows 10 PC. I hesitate to even mention this, but advanced users could add support for TLS 1.2 to IE9 if they so desired (see my thread IE9: Last Supported Browser for Vista).
boxes with red x mean that the image is not loaded, you may need to click on download images where it says images blocked to protect the identity of the sender
btw unlike vistaar said vista is safe to use if you have a good paid antivirus like norton or even a free one like avira keep your pc, win 10 is not that good unlike most ppl say