If you count the updated emails as the ones that have changed and not ones that are already valid without needing the change I have an idea - if not, disregard this post :-)
To use one of red's ideas why not start a new topic asking people to check their email addresses are valid then post once and only once in the thread to say that it's correct.
Red did it to see how many people actually read a.o a while back and it was popular, there's no reason why it couldn't work in this situation.
After a couple of weeks, or a month you'll be able to get a better idea of the validity of the addresses.
--edit--
Wayne posted as I was typing this... :-)
