126.96.36.199.3.4 Sending Updates to New Attendees Only
When a significant change, as specified in section 188.8.131.52.3.1, has not been made and the user has added attendees, the client MAY send the Meeting Update object to only the new attendees or prompt the user asking whether the user wants to send the update to all recipients (2) or only to added or removed recipients (2). The client SHOULD<53> treat an attendee as a new attendee if the value of the recipSendable bit of the attendee's PidTagRecipientFlags property (section 184.108.40.206.1) has changed from 0 to 1. When sending a Meeting Update object to only new attendees, the client SHOULD<54> add all other attendees (for example, those not receiving the Meeting Update object) into the PidLidAppointmentUnsendableRecipients property (section 220.127.116.11) on the Meeting Update object. For each attendee added to the PidLidAppointmentUnsendableRecipients property, the client sets the recipOriginal bit of the PidTagRecipientFlags property (section 18.104.22.168.1) of the attendee's RecipientRow structure, as specified in [MS-OXCDATA] section 2.8.3, if the recipSendable bit is set, and sets the recipSendable bit to 0.