The calendar invites sent to the host and client depend on whether the host has integrated Google Calendar.
Scenario 1
The host has integrated Google Calendar with NeetoCal.
In this case, when a client books a meeting, NeetoCal creates a calendar event in the host's Google Calendar. The client is added as a participating member.
If the client is using Gmail, the calendar event is automatically added to the client's google calendar as well by Google.
Scenario 2
The host has not integrated Google Calendar with NeetoCal.
In this case, when a client books a meeting, NeetoCal sends emails to the client and the host. Since the host has not integrated Calendar, we cannot add a calendar event to the host's calendar.
Similarly, NeetoCal can't add the calendar event to the client's calendar because we don't have permission to do it. If the client wants to add this event to their calendar, they can do it by clicking the "Add to calendar" link in the email.