I noticed that a client was not able to create mailboxes because the domain did not appear in the select box. I then discovered the possible reason. The hosting plan was supposed to be email-only but the reseller had forgotten to activate the email; it had no service at all. This apparently still allowed the reseller to create the domain, but it did not show up in the client's email manager. I think this is bug nr 1. When the hosting plan does not include email, then in no circumstance should the email manager appear in the client account.
Then I enabled the email in the hosting plan. This change did not propagate to the client account until I deleted the domain and recreated it. Now I don't know what is the expected behavior in this case. Should the change in the hosting plan propagate to the client domain? If so, then this could be considered another bug.
Since this is a production environment, I am reluctant to do more experiments. May be Herr Keppler & Co can try to reproduce it on a test system? Not very important of course, but I still report it here for completeness.