I have the same problem in my site. If you take a peek in my beagle site you will see photo's everywhere in there.
BUT
If they post a photo to large it is deleted immediately. Their account is noted. And they are reminded of the size restriction.
If they continue to ignore the size rule they get a 30 break from posting in the site. If they continue to ignore the posting size restriction they get a 90 day vacation. And after that if they continue to ignore the rules they get a permanent vacation.
