Nowadays it is quite easy to scan official documents such as identity cards and vehicle registration documents and to forge them using image editing software. So never completely trust documents sent by e-mail.
Always ask for the original documents when you meet the seller and match the vehicle identification number. It is typically located under the bonnet and embossed on the body of the vehicle. On many modern vehicles there is also a “visible VIN” on the front windscreen.
This is the only way to verify that the vehicle documents are those of the vehicle you inspect.

Never provide your own vehicle documents electronically, as they might be misused for criminal purposes.