I received an .ics file that is a reminder for a Calendar Software.
I know some Microsoft applications can open it but I found no Linux programs that can open it.
I tried to import it in KOrganizer, but it would not open that file extension.
This did not work for me.
We can open an .ics file directly using Evolution, KOrganizer or Calendar. But it is sad that Ubuntu default mail client is unable to add the .ics directly to the calendar system.