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).