i LUCKILY sent mine in today. i finally got around to doing it and realized two of mine had 14 day postmarks. i used the meter machine at work *ahem* and double score, somehow the day is off by one on the machine, so the meter stamped it december 9th instead of december 10th.
i photocopied the envelopes i sent everything in so they won't try to argue i "mailed" it after the deadline because it was postmarked definitely before. even if the post office restamps it again, it would have the 10th's date, which is the 14th day, and i walked to the post office and dropped it off in their slot for today's mail to make sure.