AFAIK it’s only available as an android application. But I haven’t looked into compiling it locally or anything. It might he possible.

I’ve been using it for comms with some friends and family when we’re out of conventional network range. It works great, the pairing process is a bit of a barrier for securitu-muggles, but it works perfectly.

My only annoyance is that I can’t run the mailbox program on a regular Linux/docker server.