Mail armor is at level 40, but beware to craft these pieces you train in Leatherworking. I've seen people post that they got to 225 Blacksmithing wanting to know when they can craft Hunter level 40 Mail armor. It is sad. All that time wasted. Hunter Mail armor is actually crafted through Leatherworking 225 > Dragonscale Leatherworking. Once you hit 225 Leatherworking you can train in Dragonscale Leatherworking which has recipes for Hunter Mail armor. Remember you must be level 42 to obtain this.