Receiver of notice claims he received empty envelope. how to prove ?

How do I send a notice / legal notice to someone? Speed Post and/or registered post is the norm. Right? The notice can be tracked on India Post website using the speed post/registered post reference number and accordingly the same can be used to establish proof of service of notice. But what is the recourse if the receiver claims that the envelope was indeed received by post but it did not contain any letter or it contained newspapers or say other irrelevant content. For discussion sake, this is a genuine problem. The Hon Court registrars and/or advocates can actually post an empty envelope. Or the same can be deliberate mala fide as well to post an empty envelope or irrelevant content, then claim from post office tracking website that a notice was delivered. If mala fide, this can lead to erroneous and disastrous consequences like ex-parte order etc. Whereas, the receiver has not received any document and the Hon court acts against him.