Hi fliebe92,
thank you for your reply. I watched a video yesterday and saw, that the person changed in the email settings of zammad at notification-sender the string <noreply@#{config.fqdn}> to the actual email adress.
Now it worked to add the smtp settings of my mail provider.
I just followed the installation documentation and hit the wall quiet early. When trying to install by portainer, where could I find logs that can be of help?
Here is the video: https://www.youtube.com/watch?v=AjIoNgyOCe0
EMail configuration starts at minute 15:00 and the step, where he changes the replyto, which fixed the problem for me, starts at 16:20