Laberpferd@HistoPol
I strongly suggest you chck them out
XMPP is a classic since decades, but has somewhat falen out of fashion after it was abandoned by Bigtech
Matrix still has issues with key sharing across multiple devices, but is emerging pretty well in Mastodon and i also have heard that Thunderbird has an Matrix client function in paralell to E-Mail
All GNU social JP content and data are available under the