Look into WInlink. You have to have an amateur radio license, and you’ll have to choose between different software (ie: radio modem), and you’ll need an HF transceiver. Once licensed you can create a Winlink account (via radio, no web signups!), which gives you access to smtp through their gateways (which are actually owned by other hobbyists). Different towers/repeaters have different specs/protocols (PACTOR, Packet, I use VARA) but all of them allow you to send email to any domain or recipient, just like regular email. Hardest part is configuring your laptop (or even phone) to control your transceiver to send the signals out. The email you’d have is your_callsign@winlink.org and with HF frequencies you can hit just about any gateway listed here https://winlink.org/content/gateway_locations





Yeah it is a lot of fun, last week I was talking to a guy in Ireland just to switch bands and talk to another guy in New Zealand.
It’s actually easier than ever to get in. You can get a decent handheld UHF/VHF local rig for less than $30, and a decent QRP HF global rig runs about $225 after you upgrade your license. There’s study guides out there for $10 (and even free ones) that go over the actual questions you get on the FCC exam. The license fee has gone up to $35 from $10, but the equipment has gotten cheap enough for anyone to get in.