@kill_9_1 @farooqkz @treefit What you're describing equally applies to all federated protocols. In fact XMPP and Matrix are even better in this regard because they (optionally) route their traffic through regular HTTPS, which is impossible to distinguish from regular Web traffic. To block DeltaChat one can easily block IMAP traffic to every server other than the big providers. Given how centralized e-mail is, the fallout would be negligible.

@farooqkz @treefit While email was already there, email is not instant messaging. DeltaChat uses infrastructure built for email to deliver instant messaging. The mailbox server used in the chatmail server, dovecot, was first released in 2002. XMPP was first released 1999.