I shoot my photos in raw format. When you are asked to submit the original photo for proof, can you furnish the photo that you opened in RAW and adjusted while in RAW?
RAW adjustments don't actually change the image, it just writes a file note to the image for viewing. So yes, adjust your RAW as much as you like before converting, but for validation send your RAW and it IS original. No worries.
Careful! It is NOT true that all image editing software leaves the RAW file untouched. I've learned through personal experience that the Nikon RAWEditor actually writes to the original file. BAD Nikon!
On the same subject to save a thread, I'm curious how you want the raw files submitted. My camera produces 10 or 15 megabyte files depending on whether compression is turned on. I don't think my ISP will allow me to send a file that big. Does DPC have an FTP site that we can submit to?