Dear Marcusbs, yes now I can add a mailing group with the old interface.
But there are two things that I have a problem with:
1. The “Test imap connection” button is not working. When I pressed the button it changes in to “Working….” but there is no response at all.
When I looked into Troubleshooting it tells me: Success: Connection Successful!
2. When I send a mail to the Group email address it keeps sending the latest email over and over again and I had to manually remove the mail from the inbox before it stops. This looks like a bug to me.
Thanks for your time and hopefully you can solve the problems I have!