IMAP
IMAP messaging - isnt that just email? IMAP has been used to message people for absolutely ages!!
That's my coat with port 143 in the pocket
The company that writes the open-source software for three-quarters of the world's Internet Message Access Protocol (IMAP) email servers has a plan that could kill off proprietary chat services like Facebook's WhatsApp. And that means you, too, Slack. German open-source software-as-a-service operation Open-Xchange acquired the …
I has a little birdie on my desktop.
Now, I've seen some interesting, sometimes rather shady plugins for this little birdie. But what it ships standard with (at least in my experience) covers sufficient ground to keep me communicating with the rest of the world. Annnnnnnnd ... it does E2E where the protocol supports it....
Aaaannnnnnnnnnd I have logs. All grouped neatly together in a bunch of folders. grep suffices. Now, the E2E and logging ... .at least the *message* in flight is encrypted. I've not seen a function that will let me *log* the encrypted message in its encrypted form. And I doubt that file transfer data could be stored on disk in encrypted form...........
/wanders off to talk to someone that knows more about how to handle this ....