I just got from one of my trading partners an empty envelope that looks like the glue was never licked and sealed. And the top right corner is cut/ripped off. What should I do about this. Not naming any names as I just let him know, but just in general.

I would speak to your trading partner to try and figure out a solution. As per the deckbox rules, when you agree to a trade by mail, it is each trader's responsibility that their cards make it to their trading partner (regardless of whether the USPS screws up) - hence the reason for the suggestion that tracking be used.

In either event, you and your trading partner need to work something out. I'd also provide pictures of the envelope the way it arrived if possible.