Don’t panic! You have options. First, you can always just drop mail in the blue collection box. That’s a 24/7 operation. It doesn’t care about Saturday hours. It just wants your letters.
Need stamps? You can buy them at ATMs, grocery stores, and online. You can even print shipping labels from home and schedule a free package pickup. Yes, the mail carrier will come to your door on Saturday to grab your box. They’ll even knock, but only if you ask nicely. It’s like a very practical, very reliable fairy godparent.