Microsoft has announced that from 31st October 2017, outlook clients using RPC over Http protocol to connect to Office 365 will be no longer supported. Only Mapi over Http clients will be in action onwards. This announcement has left many administrators thinking, What exactly does that mean for my organization? What actions are required to avoid any business impact? Is it time to update outlook clients and upto what level? And last but not the least how can I verify if all necessary steps have been taken to ensure business as usual. Lets try to answer these questions one by one.
So what does this announcement means for any organization? In simple words, any outlook client which still use RPC over Http to connect to Office 365 will be retired and hence would require to be updated if possible. This means that outlook 2007 and earlier versions will be retired and will be no longer able to connect to exchange online. So, this would require following actions from Office 365 administrators.

  1. Update Outlook 2007 or earlier versions of outlook to latest outlook version.
  2. For outlook 2010 and higher minimum required updates are following :
Office version Update Build number
Office 2016 The December 8, 2015 update
  • Subscription: 16.0.6568.20xx
  • MSI: 16.0.4312.1001
Office 2013 Office 2013 Service Pack 1 (SP1) and the December 8, 2015 update 15.0.4779.1002
Office 2010 Office 2010 Service Pack 2 (SP2) and the December 8, 2015 update 14.0.7164.5002

Note The December 8, 2015 updates for Office are listed in Microsoft Knowledge Base article, 3121650: “December 8, 2015, update for Office”. It is  recommended that you keep outlook clients updated with the most recent product updates as several MAPI over HTTP issues have been fixed since December 2015.
Additionally, you may have to make sure that Outlook clients aren’t using a registry key to disable MAPI over HTTP. For more information, see Microsoft Knowledge Base article, 2937684 : “Outlook 2013 or 2016 may not connect using MAPI over HTTPs as expected”.
Now while you make all efforts to ensure you meet the deadline and take all necessary steps to update your environment, you do not need assurance that you have completed your job. A simple report providing information from office 365 about outlook clients connecting to your tenant should do the job. Lets get this report now following below steps.
To retrieve this information, enable owner access auditing for each mailbox, and then query the audit log for the Outlook version that’s used to log on to the mailbox. To do this, follow these steps:

  1. Connect to Exchange Online using remote PowerShell.
  2. Enable mailbox auditing for the owner. To do this, run one of the following commands:
    • For one mailbox:
    • For all mailboxes:

Note: Mailbox auditing may take up to 24 hours to get enabled.

  1. Search the audit log. To do this, run one of the following commands:
    • For one mailbox:
    • For all mailboxes and export results to a .csv file

The above powershell command will produce a comprehensive report which you can use as a guide line to ensure that all your clients are ready for switch to Mapi over Http. Here is a sample output.

Exchange, Office 365, PowerShell, Uncategorized
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