Never e-mail vehicle certificates or identification documents when selling or buying a car!
Receivers of digital documents have no problems to masquerade under the identity of the actual owner of the documents and act in his or her name. This does not necessarily require the identity thief to forge the documents using editing software. In the worst case, electronic documents can be used to commit a crime such as for instance fraud in the name of the rightful owner. This could have rather unpleasant consequences as e.g. criminal prosecution.
Be careful! Never copy or scan and e-mail vehicle certificates or identity papers to interested buyers!