The previous poster was right about the new window hours ending at 10pm on weekdays, but Saturdays it's 9pm (NOT 8).
This is quite important, because I would suggest getting there as close to closing as you can (8:50) unless you want to be spending hours of your Saturday waiting 'on' line. This is for a few reasons, people don't know it's open until 9 and not 8, and the workers are eager to leave, so the line is usually cleared by 9:30. But the postal police won't let new people get in the line after 8:58-ish, and they'll threaten to arrest you if you even try; they get in arguments with people every night. (the lobby is open 24/7, including the APC kiosks, but the last collection is right before the windows close)
Sundays they are open until 7.
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