Last Updated: May 1, 2018
ISSUE
You may be unable to search or cannot see MailTips or Free/Busy.
When viewing Free/Busy you may see the error:
"No free/busy information could be retrieved. Your server location could not be determined."
This issue occurs on Build 8420.xxxx and higher. A recent Outlook 2016 change affects the User-Agent that causes problems with the Exchange EWSAllowOutlook feature.
The agent changed from:
User-Agent: Microsoft Office/16.0 (Windows NT 10.0; Microsoft Outlook 16.0.8201; Pro)
To:
User-Agent: Microsoft Office/16.0 (Windows NT 10.0; MAPI 16.0.8528; Pro)
Note: EWSAllowOutlook looks for "Microsoft Outlook" and not "MAPI". The effect with the Exchange server configured with EWSAllowOutlook will not allow Outlook to use EWS. This will present as a 403 error back to the client. This breaks EWS and REST.
STATUS - Monthly Channel: FIXED
This issue is fixed in Monthly Channel Version 1804 (Build 9226.2114) and higher. To get the latest update immediately, open Outlook and choose File > Office Account > Update Options > Update Now.
STATUS - Semi Annual Channel: WORKAROUND
For Semi Annual Channel, the fix is estimated for May 8th 2018, in Builds 8431.2250 and higher. In the meantime, you can use the following workaround:
On the Exchange server use the below cmdlet to work around the problem:
Note: You will need to use PowerShell to run these commands. For more information, see Connect to Exchange Online PowerShell.
-
If the setting is per user, use this command: Set-CASMailbox user -EwsAllowList @{add="*MAPI*"}
To confirm the setting was applied, run this command: get-casmailbox user | fl *ews*
-
If the setting is at the organizational level, use this command: Set-OrganizationConfig -EwsAllowList @{add="*MAPI*"}
To confirm the setting was applied, run this command: get-organizationconfig | fl *ews*
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See Also
Fixes or workarounds for recent issues in Outlook for Windows
