Exchange Online RPC over HTTP Deprecation(Outlook 2007) October 31 2017

Status: Active

Action Required by: October 31, 2017 at 5:59 PM UTC

Details: On October 31st, 2017, Exchange Online mailboxes in Office 365 will require connections from Outlook for Windows use MAPI over HTTP, our new method of connectivity and transport between Outlook for Windows and Exchange. In May of 2014, Microsoft introduced MAPI over HTTP as a replacement for RPC over HTTP. RPC over HTTP was a legacy connection protocol that is being deprecated from Exchange Online. Beginning October 31, 2017, Outlook for Windows clients using RPC over HTTP will be unable to access their Exchange Online mailbox. The necessary action depends on the version of Outlook in use in your organization. If you are using Outlook 2007 or earlier, you need to upgrade. Outlook 2007 does not contain support for the MAPI/HTTP protocol. We encourage you to update to the Office 365 ProPlus subscription, or access Outlook via the web browser (which is included in your current subscription plan). Outlook 2010-2016 customers will need to ensure their version of Outlook for Windows is set up to support MAPI/HTTP. At a minimum, you should ensure you have installed the December 2015 update. Lastly, ensure your Outlook clients are not using a registry key to block MAPI/HTTP.

Message Center: MC85988 – Potential service disruption for Outlook for Windows users

Posted: November 16, 2016

Additional Information: KB3201590: RPC over HTTP deprecated in Office 365 on October 31, 2017

Outlook 2007 and Exchange 2013 not a real good combination

Exchange 2013 and Outlook 2007 is a interrested thing

Outlook 2007 SP3 is supported with with April 2014 Public Update KB 2863811

For you as a System or Exchange administrator or Consultant you might consider some things before migrating to Exchange 2013.

You can’t share your calendar in Outlook 2007
When you use Microsoft Office Outlook 2007 to share your calendar, you receive the following error message:

Error while preparing to send sharing message.

Also, if you try to check the permissions on the calendar, you may receive the following error message:

An error occurred when setting schedule permissions.

Solotion Microsoft: Using OWA

It works for share the calendar and you can set editor calendar permissies. All other permissions are not availible


  • Accessrights Missing

    With Powershell you can set the permissions

Add-MailboxFolderPermission –identity (username+’:\calendar’) –user testuser –Accessrights PublishingEditor

Better solution

Upgrade your Outlook Client to 2010 or 2013

Outlook slow after migrating to Exchange 2013

Outlook can be slow in Online modus sometimes when you move mailboxes to Exchange 2013. I seems that Windows 7 with Outlook 2007/2010 & 2013 sometimes have some issues.

Before applying this TCP Ack solution, the below conditions must be met:

– OWA connection and mail browsing is very fine, whereas an Outlook online mode (i.e. not cached mode) connectivity is quite sluggish when mailboxes are on Exchange 2013…

– If OWA is slow as well, then the issue may be a general network slowness issue – check the network latency using Ping

– On Outlook Connection Status dialog box (CTRL+Right Click the Outlook icon on the Windows notifications part of the taskbar), Avg. Proc. time is fine, below 50~60ms, and Avg. Resp. time is over 110ms.

More information about the TcpAckFrequency registry key:

Quoting from

– TcpAckFrequency is a registry entry that determines the number of TCP acknowledgments (ACKs) that will be outstanding before the delayed ACK timer is ignored.

– TCP uses delayed acknowledgments to reduce the number of packets that are sent on the media (Wifi, Wire,…)

– As data is received by TCP on a particular connection, it sends an acknowledgment back only if one of the following conditions is true:

  • No acknowledgment was sent for the previous segment received.
  • A segment is received, but no other segment arrives within 200 milliseconds for that connection.

Typically, an acknowledgment is sent for every other TCP segment that is received on a connection unless the delayed ACK timer (200 milliseconds) expires.

– You can adjust the delayed ACK timer by editing the following registry entry.


HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\<Interface GUID>



Value Type: REG_DWORD, number
Valid Range: 0-255
Default: 2
Description: Specifies the number of ACKs that will be outstanding before the delayed ACK timer is ignored. Microsoft does not recommend changing the default value without careful study of the environment.

$strGUIDS=[array](Get-WmiObject win32_networkadapter -filter “netconnectionstatus = 2” | select -expand GUID)
foreach ($strGUID in $strGUIDS) {New-ItemProperty -path HKLM:\System\CurrentControlSet\services\Tcpip\Parameters\Interfaces\$strGUID -propertytype DWORD -name TcpAckFrequency -value 1}


KB2888049 Update is available that improves the network performance of Internet Explorer 11 in Windows