Earlier quoted context omitted.
Some mail machines cut thick or oversized envelopes by accident sometimes. So this might not have been tampered with. The right way to deal with anything you receive by mail is to return to sender, as long as it has a return address. Cross out your address, clearly write RTS on the front and in small write e.g. "item not sealed on arrival / tampering" or something, then stick in a post box. The sender has more recour…
Unfortunately, in this case the item was delivered by Royal Mail themselves and left in our mail box, so there was no opportunity to do anything like that. I might have bought the idea of a mechanical issue causing the opening if it had been a clean cut and the contents had been otherwise undisturbed, but with a very rough tear and the contents having apparently been shoved back into the envelope, it seems rather les…
When an envelope gets jammed in a sorting machine and some postal worker has to quickly clear the jam, stuff the contents back, and restart the machine, what you receive will look like a complete mess.