Sun, 08 Apr 2018 15:03:00 +0900 Yuya Nishihara py3: use system string to access email headers
(0) -30000 -10000 -3000 -1000 -300 -100 -30 -10 -1 +1 +10 +30 +100 +300 +1000 +3000 +10000 tip