“Winlink Global Radio Email®️ …is a network of amateur radio and authorized government-licensed stations that provides worldwide radio email using radio pathways where the internet is not present.” (http://winlink.org)
The content of this page is expanding, but for now, here are a few pages to assist you with some basic Winlink functionality.
Sending a new Winlink message
Replying to a Winlink message
Sending a Winlink message with an ICS-213 Form