A lot of messaging systems try to reinvent the email system but many (signal, matrix, xmpp) took over one key traditional design which we actually dropped while retaining SMTP/IMAP compatibility: server-controlled identities.

With #chatmail user identities are cryptographic and reside on end user devices only. Servers are only message relays and have no control over identities or chats, only perform fast message routing. See this fosdem talk by one of our lead developers https://mirror.cyberbits.eu/fosdem/2026/ud2218a/3F9VTU-deltachat-chatmail-relays-multi-transport.av1.webm