Summary:

A customer cannot modify their Exchange appointments in CRM, so their list of Pending appointments keeps growing.

Steps to reproduce:

1. Using an Outlook user not synched with CRM, create an appointment, and invite a CRM Exchange integration user.
2. As the CRM Exchange integration user, log into your inbox using Outlook or OWA, and accept the appointment.
3. Run the Exchange synch.
4. The appointment appears in CRM with a status of "Pending".

Expected result:

The user should be able to change the appointment status.

Actual result:

The appointment is read-only.

Symptoms:

The following info message is displayed in CRM:

Exchange sync info: This appointment has synchronised from the Exchange Server mailbox belonging to the CRM User listed in the "User" field below. It is not possible to edit this appointment in CRM as it is an "invitee copy" of the original Organiser appointment.

Work around / Resolution:

This is by design. You're looking at a stub appointment. This appointment is read-only in CRM, and is liable to be overwritten at any time by changes made by the organiser. The Outlook UI allows invitees to amend their copies of the appointment, but if the organiser updates their copy, their changes will be wiped out. Rather than do this, and have the appointments changed unexpectedly, the appointment is just made read-only in CRM.

There's further information available here:
https://community.sagecrm.com/user_community/b/sage_crm_news/archive/2011/08/02/the-importance-of-being-the-organizer-a-primer-for-exchange-integration-appointment-sync-rules.aspx

https://community.sagecrm.com/user_community/b/sage_crm_news/archive/2011/08/31/exchange-server-integration-stub-appointments-explained.aspx

There's a few articles in this series - there's links available for the rest of them at the bottom of either of the above articles.