Winlink …a worldwide amateur radio email service 

that uses radio pathways where the internet is not present, and is capable of operating completely without the internet–automatically–using smart-network radio relays.  https://winlink.org/

Easy Steps: learn a little about Winlink, without using an amateur radio:

Winlink Without Radio, by Bill Thomassen N6NBN (March 2019)

…and now with a radio:

Introduction to Winlink: Email Over Radio (N6NBN) (Feb. 2018)

For a good local source of additional information see: 

https://wiki.psrg.org/wiki/Winlink:_Internet_Email_over_Radio