The voting mechanism could also be implemented on forums (where its probably a lot easier to do), and ingame would just include something along the lines of "Check out this new suggestion that might interest you, and voice your opinion at {link}!", in the mail.
In the past, we had a voting system for suggestions on forums, but it was removed with V8, and also wasn't really used to consider suggestions because most suggestions arent a simple "yes" or "no".