Cartoon Network releases their ratings around the first of the month which displays ratings for shows 2 months prior. (in other words, when February starts we'll get the December ratings) So we won't find out how Futurama did until March.
Yeah it sucks.
Oh, and Adult Swim does encourage emails. All can be sent to
adultswim@turner.com . Although it's much like
askfox@fox.com and sends copied responses to multiple people.
(And just for the curious, CN's #1 show so far this season has been Dragon Ball Z which got a 3.2/7 rating.)