As I’ve understood, Delta chat is based on the IMAP protocol and uses the infrastructure of your email provider. Thus, it uses no own server infrastructure, but has the also the downsides of the protocol and some issues with many email providers.
Wikipedia.de - Delta Chat (no English version available yet)
some issues with many email providers
This turned out to be the deal-breaker for me. GMX kept locking me out of my account because of the DeltaChat messages. They’re (of course) full of cyphertext and to email providers this must look a look like spam.
The open-to-abuse nature of email claims yet another victim.
On the other hand, GMX (and web.de) is a notoriously bad influence on email communication and will randomly block mailservers if they feel like it while flooding all of their own users with spam. The world would be a better place without 1&1 / united internet.
But it’s a free Europe-based provider that’s not US big tech. A better suggestion?
To be clear, I use a paid service (Mailbox.org) for my main email, as everyone should do.
