In opposite to “Provider overview” provider “t-online.de” needs some preparation before working with deltachat.
Deltachat shows progess until 68% and then error message appears.
Automatic setup doesn’t work.
Server settings are (working):
secureimap.t-online.de:993
securesmtp.t-online.de:465
With new email account external access isn’t possible from scratch.
You need to specify an extra password for external account access at web interfaces settings!