@Adpower99: the MRF issue has nothing to do with the quality or the saleability of an image - so it's not a real reject. It's more an administration issue on your side. Get that release, and if it's not possible any more, try editorial if it has editorial value.
@Mocker/Wisconsinart: yes there is a gray zone, and by borderline I didn't mean technically but concerning usability. It's a very subjective area and reviewers might be more experienced in it since they have a global overview. The "error" margin might even be 10%.
Also consider the time and energy involved in arguing about rejects, time that can be used to shoot and edit other shots.
Every (large) agent has a certain idea where his collection is going to, content wise. An image that might fit one collection might not fit another. Rejects for LCV (low commercial value) and "enough of this" can be very frustrating, but if you're an independent, other sites might make up for the frustration.
I always got a "non-canned" reply from support@dt.com, but I figure you should make a clear factual case in your objection, like give search results with few images for rejected images that are deemed "overabundant". posted in Contacting senior support.