Thanks for the workaround.
The system now accepts the second email address with no problem.
However, the email notifications are still not being consistently received. Sometimes they come, sometimes they do not.
My hoster thinks it might be his sendmail.
Is there a way I can tell PivotX to use smtp to send mail instead of sendmail?
That might fix my issue with inconsistent notifications, see this thread viewtopic.php?f=2&t=2741#p14287
Best regards and thanks,