Osama bin Laden was a prolific user of email for many years, evading the global intelligence community by using simple, cheap tech: USB sticks.
His system depended on couriers who would use internet cafes, checking in to his anonymized email accounts and copying incoming messages to a simple USB memory stick.
They’d take he stick back to bin Laden’s Abbottabed compound, where he’d read and reply to his messages offline.
Then the couriers would head back out again and repeat the process in reverse.
This kind of file transfer even has a name: sneakernet. It’s slow, but it works. And relatively secure, as long as you don’t misplace your USB stick.
The idea’s been around since the days of floppy disks (kids: look it up), when it was easier to copy files by carrying them from one computer to another, than it was to get the two computers talking to one another over a network.
Kids: stop laughing. We grew up just fine without Wi-Fi.