Family members of mine who are retired have been experiencing issues with Windows Mail that came with Windows 8.0. I updated their PC to Windows 8.1. However, I don't believe Mail that came with the Mail, Calendar, and People app was updated. How do I update to the reportedly much improved app that was released with Windows 8.1 while preserving their current mail folders and contacts? Thanks.

Hi,

Generally speaking, Mail APP would have update alert if there is any update. If not, it means current APP was already upgraded to be latest. Other apps too. 

In my opinion, if you concern current app need to be upgrade, you can try to remove it from Windows. After that, access to Store to download the latest app version.