Did they specifically address you about bandwidth usage or was it a general memo? In case of the latter, it's most likely addressed at folks downloading all kinds of stuff (music, movies, software). I can tell you that this can easily amount to many 100s of gigabytes per month (not from personal experience, of course

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While a session of EQ2 will likely use more bandwidth than just regular browsing, it's probably not nearly enough to register on any 'excessive bandwidth usage radar'.