When I worked in an office job (before e-mail was invented) (yes, I am retired now) I had an episode like that. We were clearing out a store room and I came across an old briefcase, which rattled, and was locked. Our orders were to throw such things out but I thought I should first find out what was inside. The three-wheel lock on the cheap briefcase was easy enough to fiddle in my lunch break (didn't even have to brute-force it by the numbers). Found discussion papers from a long-past interstate conference, and the used airline ticket of the one who attended the conference, and half a packet of condoms. So I closed it and left it in the boss's office. In that case the moral issue was moot, because the traveler was my boss. Never heard another word about it.