Correct misleading notification from resource reservation database

If you submit a repeating invitation including a room, the server send a misleading (confusing) message to the chair in case one or multiple dates cannot be booked.

e.g. you submit a repeating (monthly) invitation (12 reservations), where one or more dates are not booked.

The message the user receives look like this:

Declined: Blocker IT Architecture Meeting
Mi. 05.02.2020 13:30 - 16:00 (Wiederkehrend)

Roomname xyz ist nicht verfügbar

But in fact the room is not available Mi 02-Sep-2020 and to find out the user needs to click on the small "+" in the mail to see the conflicts. User expects that the date in the header is "Declined".

The header should either show the "Declined" dates or point to the content of the mail ("Please see details in the mail").