https://pairdrop.net/

open source, can be self hosted or you can use the official instance.

Personally I have been using KDE connect most of the time when I am at home.

Pairdrop I use more when sharing with other people across the internet.

You can run a gui-less service that recieves and displays push notifications. I’ve programmed something like this before. I know it is technically a kind of client, but it is not an email-client.

Is the ‘%MARKDOWN’ part of your example correct? That should also be converted to a dash? Or did you forget the 20 there?