Steam ids w/o original email?

What does that exactly mean? It means that you can't change password and secret question etc. because you can't access to said mail or anything else? If i'm getting it right so someone can claim your account anytime?

 

No, it means they're older accounts with e-mail logins, and the person selling the account doesn't actually own that email.

The account I own was given to me YEARS ago by an old friend, and it is an email login. I've since gained control of the email (old Hotmail, it expired and I was able to re-create it) and I'm assuming the same concept applies to many of the aforementioned accounts

The account itself can still be associated with a different email for password resets, steam guard, etc.