Client doesnt show Messages


i tested Delta Chat for a while and encountered an Problem when trying to Chat with an specific Email-Account. I could send Messages on both ends, but while one client worked as expected, the other never showed any incoming Messages.
I looked into the Email-Account and saw that the Messages are there, but this client never moved them to the ‘DeltaChat’-Folder. I think the Problem is that the Client only searches the ‘inbox’-Folder for Messages, but my Provider doesn’t put new Emails there, they are in ‘unknown sources’, only known Friends appear in the Inbox.
I could change that behaviour, but still, this would cause Problems to other interested People as this is the Standart-Way of dealing with those things from one of the biggest Email-Providers in my country.
Is there an way to tell the client in in which folder to look for new Messages?

Delta Chat version: 0.304.0 (Android on both ends)
Expected behavior: Show the Messages
Actual behavior: No incoming messages are shown
Steps to reproduce the problem:

  1. Send an Message to an Client using a

You need to change that behavior and we need to put the additional steps description into the provider overview.

Edit: The info is already at these places - but not very detailed.
If you know how to work with markdown you can add the steps and improve the documentation on

Can confirm this at one friend: Here filter (“unknown friends”) was active too.

But at last in 04/2019 I created a new account from scratch and that worked out of the box.
Only external access needs to be granted by web interface.