- If the Chest/Furnace was unlocked, then it's fair game.
- If the Chest/Furnace was locked, then you're gonna get banned.
Plain and simple.
And about mods: If the thing is over a month old, meaning the player has not been online in over a month, I've been informed that we're allowed to REMOVE the chest/furnace/door. (And no, that doesn't mean keeping everything that's in it)