As far as I knew about this rule it was based on grinders and spawning pads. I've always known about the mobs being able to hit you rule, however I didn't realise it applied in this case. The way I have always seen it, is that if you make a grinder of some sort and the mobs are being filtered into a hole of some sort so that you are easily able to grind exp then that is illegal. I did not know this applied to making a quick box in the nether. I would like to point out that I only ever used this as minor protection against pigmen, they could still hit me and I often died even whilst in a box.
I'd also like to question the resetting of all my levels. Okay, so I broke a rule which I wasn't 100% understanding of. I am not a constant rulebreaker, I don't think I've ever broken a rule before in fact and the reason I say this is to show that the reason I have broken this rule is because of a lack of understanding, which is mostly my fault but at the same time I'd like to see more warnings from the staff. For example after doing this once I could have been reminded that it is illegal and not to do it again. Instead you've decided to use me and others to "set an example" for everyone else. You've taken away something I've been working at for days and days, and infact in most cases I was not using this 'illegal' method to level. It's not like I have been sitting there grinding pigmen to master my class, I did it a few times and you've ruined my whole experience this map so far. I'd like this action to be reconsidered or at least a more in depth explanation on the whole thing.
Also, how have you decided who's levels are reset? I have seen a few people whom I have spent time with in the nether who's levels have not reset. I'm not gonna call them out on it but um...?