Installing a recently unsupported operating system so you can use an email program that hasn’t been supported for years is something I’ll advise against. There are safer ways to go.
Older games need a different operating system than the one provided by Windows 7 or 8. With a virtual machine, you can run Windows XP (and your games) on any machine that has enough power.
When you create a backup image of your machine, it contains everything; that’s the definition of a backup image.