This relatively old digital mode is still around and appears to cover the US and Europe quite well on HF.
The latest software “Winlink-express” also calculates the most likely WinLink station that you could contact based on VOACAP propagation reports. As well as it’s own email network, it is also able to send and receive to Internet email addresses.
I suspect the issue may be work at the SOTAWatch website end to accept such data unless I can find a Winlink-SMS gateway somewhere.
Perhaps worth considering - or has this already been tried / discussed - I have searched this reflector and found nothing so far.
Looking for SMS to Winlink, I found thaere’s actually a Winlink to APRS gateway -
I’ll continue searching …
Perhaps it might even be possible for the activator to receive the last say 5 spots this way through Martyns system if it’s still running: