Outlook – Appointment showing as tentative even after accepting it multiple times

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I am experiencing this weird issue with Outlook 2013: I have several appointments in my calendar, but no matter how many times I accept one of them (this happens to two appointments actually, the others seem to work just fine) it just goes back to Tentative after a few seconds.

It shows correctly on iOS however, which leads me to think that the issue might indeed be on the Outlook side. Any thoughts?

Some more information

I am using Outlook 2013 on Windows 8 and the default calendar app on iOS. Every action I do is performed in Outlook, I use the phone only to view information and not to act on appointments.

Behavior in Outlook: the appointment initially shows as tentative in my calendar before accepting it (correct behavior), then I accept it, it shows as accepted for a while before turning back to tentative (after a few seconds).

On iOS: the appointment is correctly shown as accepted.

Best Answer

This is not exactly a solution, just what I have found out about the problem.

As far as I can tell, this bug exists in Outlook since a long time. For example, I have found a reference to it from 2009 in the thread Exchange Calendar Invites Reverting to Tentative After Accepting:

We are using Exchange 2003 with the latest serivce packs, clients have Vista sp2 with Outlook 2007 sp1. The affected users do not have delegates. As long as the iPhone is not syncing the calendar, the meetings show as busy. When iPhone calendar is on, meetings revert to tentative within a few minutes. None of the solutions presented in any of these forums have worked.

I have not been able to find anybody who claimed to have solved this problem, except by disabling the option of introducing invites into the calendar as tentative.

However, the above text seems to hint that it is the iPhone resync that actually deranges the Exchange server.

One explanation is that the bad appointments were loused-up in the Exchange database by the iPhone resync, so that the iPhone shows the status as it understands, while Outlook shows the status as it understands. Thereafter, both iPhone and Outlook just continue to mishandle the appointment.

You could test this theory by trying to see if new appointments can go bad while the iPhone is turned off.

In the Outlook CLient

You can disable the functionality from the Outlook client, but I don't think the option exists in Outlook 2011 for Mac.

In OWA - Outlook Web Access

Log into OWA using the address provided by your Exchange Administrator.
Click Options in the top-right corner of the window and then choose See all options...
Choose Settings and then select the Calendar tab
Uncheck the box for Automatically place new meeting requests on my calendar, marked Tentative

Source for steps

Using the Exchange Powershell console

Alternatively you should be able to disable them per-user from the Exchange server itself (Source):

Set-CalendarProcessing -Identity "user name" -AddNewRequestsTentatively:$false

Note that changing this parameter is only supported for resources (rooms, equipments, ...). To disable it for regular user, one has to temporarily change the account type (Source).

Get-Mailbox -Identity "user name" | Set-Mailbox -Type Room
Get-Mailbox -Identity "user name" | Set-CalendarProcessing -AddNewRequestsTentatively:$false
Get-Mailbox -Identity "user name" | Set-Mailbox -Type Regular

If you want to completely disable the calendar attendant, set AutomateProcessing to 'none':

Get-Mailbox -Identity "user name" | Set-Mailbox -Type Room
Get-Mailbox -Identity "user name" | Set-CalendarProcessing -AutomateProcessing:'none'
Get-Mailbox -Identity "user name" | Set-Mailbox -Type Regular

Best Answer

Related Solutions

Exchange 2013 appointments accepted as tentative without user’s knowledge

In the Outlook CLient

In OWA - Outlook Web Access

Using the Exchange Powershell console

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