Many messaging developers and Exchange administrators are not aware of possible effects of MailboxCalendarSettings settings.  While these options provide much needed capabilities which remove the need for specialized code, caution should be exercised as MailboxCalendarSettings can drastically affect any calendar related item in Exchange.  Some of the settings will trigger other settings be active when changed - an example is setting the AutomateProcessing flag to AutoAccept, which  causes other settings to become active and the defaults for those other settings are highly undesirable for some customers.  It’s important for every Exchange messaging developer and administrator to review the full settings available so that you are aware of them before changing these options or troubleshooting related issues.


Set-MailboxCalendarSettings (Exchange 2007)


Set-CalendarProcessing (Exchagne 2010)


You can check mailbox settings using get-mailboxcalendarsettings.  With these settings, OWA should be able to reproduce the same behavior messaging APIswould manifest (such as Exchange Web Services (EWS), WebDAV, MAPI and Exchange ActiveSync (EAS).  If you have both a repro and non-repro box mailbox, you should consider getting a list of the settings in both mailboxes and comparing – below is the command for pulling the settings of the “equipmailbox” mailbox. 


[PS] C:\Windows\system32>get-mailboxcalendarsettings -Identity equipmailbox | fl

AutomateProcessing                  : AutoAccept
AllowConflicts                      : False
BookingWindowInDays                 : 180
MaximumDurationInMinutes            : 1440
AllowRecurringMeetings              : True
EnforceSchedulingHorizon            : True
ScheduleOnlyDuringWorkHours         : False
ConflictPercentageAllowed           : 0
MaximumConflictInstances            : 0
ForwardRequestsToDelegates          : True
DeleteAttachments                   : True
DeleteComments                      : True
RemovePrivateProperty               : True
DeleteSubject                       : True
DisableReminders                    : True
AddOrganizerToSubject               : True
DeleteNonCalendarItems              : True
TentativePendingApproval            : True
EnableResponseDetails               : True
OrganizerInfo                       : True
ResourceDelegates                   : {}
RequestOutOfPolicy                  :
AllRequestOutOfPolicy               : False
BookInPolicy                        :
AllBookInPolicy                     : True
RequestInPolicy                     :
AllRequestInPolicy                  : False
AddAdditionalResponse               : False
AdditionalResponse                  :
RemoveOldMeetingMessages            : True
AddNewRequestsTentatively           : True
ProcessExternalMeetingMessages      : False
DefaultReminderTime                 : 15
RemoveForwardedMeetingNotifications : False
Identity                            :


With the example above, the Subject line of every meeting will be replaced by the Organizer’s name when a meeting request arrives and is added to the calendar of this mailbox.  The mailbox had been created as an equipment mailbox and the only option which was set was setting AutomateProcessing to AutoAccept.  Both DeleteSubject and AddOrganizerToSubject were defaulted to True when the mailbox created.  When AutomateProcessing is set to AutoAccept, Exchange will start using settings such as DeleteSubject and AddOrganizerToSubject; if AutomateProcessing were set to anything else, those two settings would not be used.      


Some examples of symptoms wich could be caused by these settings:

                Blanking or changing of the subject line

                Attachments being deleted

                Reminders being disabled

                Restrictions on the possible scopes of meetings

                …. There are many more, so read-up.