Create new event from email (show as)

When creating a new calendar event from an email message, the default Show as attribute is set to Free.
If I add a resource (from the IceWarp server) as an attendee, the resource rejects the invitation.

When I create a new event directly from the calendar, the default Show as attribute is Busy, and everything works correctly.

Is it possible to set Busy as the default value when creating an event from an email?

Thanks Martin