Rather than build a new protocol like the Matrix project, Deltachat builds a rich messaging app around one of the oldest protocols, SMTP. A benefit is that you can talk to anyone with an email. Adding a tiny local SMTP server (e.g. opensmtpd) makes this app fully decentralized, but it should be listed as federated - because it doesn't include a server out of the box.
Rather than build a new protocol like the Matrix project, Deltachat builds a rich messaging app around one of the oldest protocols, SMTP. A benefit is that you can talk to anyone with an email. Adding a tiny local SMTP server (e.g. opensmtpd) makes this app fully decentralized, but it should be listed as federated - because it doesn't include a server out of the box.