Delivery to the US

Hi guys, I'm currently trying to get paperwork to the US so I can get my kiddos passport sorted. I've been told by one friend who went to send me something that the Post Office told her they aren't accepting mail to the US right now. But Royal Mail website says that they are. I also have friends in the US that are struggling to get deliveries for their businesses from the UK. Does anyone actually know what is going on? Is any mail service sending to the US right now?