This is unclear.
You say, that you think, you deleted those emails when you uninstalled Netscape, but apparently those messages still exist, correct?
It's possible, if when uninstalling Netscape, you didn't delete your profile.
Now, we need to know, where exactly they are located in your computer (provide path), and what type of files they are (extension).
What email program are you using now?
What Windows version?