Understand the issue, however in the end, it is not sustainable or advisable to keep doing system restore.
Indeed. You need to keep moving forward with security updates for the operating system, also the time will come where the restore point in question disappears.
You really only seem to have two options. Either you find an installer for your preferred version of AOL, which you install in a virtual machine that you only use for e-mail, or concede that you have to give in to the latest version of AOL. You can't hang on to an old system forever.
I used to be a huge fan of Demon's Turnpike e-mail system. It got to the "almost brilliant" stage before development got canned with IMAP server implemented and IMAP client under development. I was one of the beta testers.
Demon felt that they could not justify the resources to continue developing Turnpike and the use of commercially licensed components with no obvious replacements lead to the decision that the code base was unsuitable for open sourcing. I persevered with Turnpike some time into the Windows 7 generation, running Turnpike under Windows XP Mode as it wouldn't run on a 64 bit OS and, if I remember correctly, would not run on any OS later than Vista. Eventually, the OS limitations, together with the limitations of the flat file database and the 4GB limit for the mail database proved too much. I moved over to a hosted IMAP solution, using Turnpike's IMAP server to export my existing mail. As I use my own domain for e-mail, it's up to me whether to stick with the existing hosting provider, move to another hosting provider, or run my own mail server.
There comes a point where you have to move on from a comfortable but obsolete solution.