How to read the labeled enron dataset categories?
Looking at the first link from your post there is an in-depth overview of the different categories. Cat_#_level_1 denotes the top level category (12 in total) whereas Cat_#_level_2 denotes the second level category (up to 19 categories, depending on the level 1 category). E.g. an email with the labels Cat_3_level_1 and Cat_6_level_2 has the label california energy crisis / california politics (category 3.6). You therefore need to combine the two levels to get to the label that belongs to the second level category.