suddenly the mail administration of each Domain is missing, There are only 2 Options left (s. picture) but one cannot setup or change any mail addresses.
I'm logged in as admin so the permissions should be no problem at all.
Thanks a lot. I asked Ionos several times for what might has caused this issue and they proposed to make a Plesk repair. Before I did that I wanted to ask here if there might be another problem. Thanks again!