"Sent a letter in the post office"

[GoesStation]

We don't need to go to the post office to send a letter.

We stick a stamp on the envelope and put in a (UK) red post box or (USA) blue mailbox in the street.

I stick it in my mailbox and raise the red lever on it to indicate that it contains outbound mail.

[Rover_KE]

Yes—we can't do that here. We envy your ability to do that.

[emsr2d2]

Yes—we can't do that here. We envy your ability to do that.

I'm not sure we do these days. During the strictest times of lockdown, going out for a nice walk to post a letter was many people's excuse for leaving the house.

[GoesStation]

The US Postal Service has been removing public mailboxes for decades for lack of use. The practice hit social media during the runup to the 2020 presidential election when a photo of a truck full of old mailboxes went around attached to outraged language asserting that they had just been removed to make voting by mail more difficult.