RMA issue without proof of purchase

I opened an RMA 2 weeks ago and here is the reply I got:

Dear xxxxx,

Thank you for contacting Western Digital and we apologize for the inconvenience. We encountered a system issue regarding RMA xxxxxxx. We are currently investigating the cause of the issue.

To assist our investigation, we request a copy of your Proof of Purchase (receipt) for your drives under RMA xxxxxx. Once this is provided, we will verify them and contact you with the resolution. Please note that this request does not constitute an agreement to replace your product, as this decision depends on the validity of your documents.

Please reply to this message if you have any further questions.

Sincerely,

Western Digital Service and Support
http://support.wdc.com/

I dont have the proof of purchase. So if I cant provide that then WD will void the warranty and deny the claim? Note that all the drives have valid manufacturer warranty irrespective of the purchase date.
After reading the policy, my understanding is that if you cant provide proof of purchase then original warranty will be reinstated based on the manufacturing date. But it does not say that the warranty will be void if the end user cant provide the proof of purchase.
I would greatly appreciate any clarification.