It could be an optional setting - if someone wants no mails, he could deactivate.
I have not the time to open my sites every 5 min to check, if something unwanted uploaded to my site. I think, a mail notification is a better solution. Just quick check your mail (with small thumbs) for new content. If something uploaded, you don't want, you can log in and delete it - or much better - click on the a link to each image in the notification mail to disable this image for a later review.
There are a lot of scripts outside, like forums, that sends out notification mails, if you want it.
I think it should be an customized notification:
- Notification enable/disable
- Notification interval (after upload each image or 1, 2, 3, ... times a hour/day)
- Notification mail with small thumbs for fast check
- "Disable" Link to each image to deactivate that image fast (maybe through API) without need login
You can make me also an offer for an custom solution for my needs or I will try to find an developer, who can do this for me.