What's new in Outlook for Office 2013 Service Pack 1 (SP1)


Applies to: Office 2013, Office 365 ProPlus, Outlook 2013

Summary: Learn about some new admin features you get in Outlook for Office 2013 SP1.

Audience: IT Professionals

Outlook 2013 SP1 includes some new features that will help the IT Pro, mail app developers, and users (which is all of us).

In this article:

  • Exchange-configurable minimum Outlook version notification means more users will update in a timely manner

  • New MAPI over HTTP Outlook/Exchange transport protocol

  • Offline Outlook data files no longer associated with a profile or email account are automatically deleted

  • The user perspective—look and feel changes to Outlook

  • For developers, extensibility for Outlook mail apps in compose forms

Are you a user?

If you’re an end-user, this article is not for you.

Are you an admin?

If you’re an administrator, this article tells you about the new features in Outlook 2013 Service Pack 1 (SP1) and introduces you to some new user features that you might get questions about.

Exchange-configurable minimum Outlook version notification means more users will update in a timely manner

We’re all guilty of postponing product updates. But doing this repeatedly means your enterprise users miss out on product improvements and in some cases could even affect the Outlook service health and reliability. The SP1 user interface (UI) now prompts Outlook users to update their Outlook client builds based on a minimum required version specified by the Exchange Server and communicated to the Outlook client by Autodiscover.

On the Exchange Server side, you’ll need to use the Set-OutlookProvider Exchange Management Shell cmdlet with the –RequiredClientVersions argument to define the minimum client build. Here’s an example:

Set-OutlookProvider exch -RequiredClientVersions "15.0.5200.1000, 2014-02-07T12:00:00Z"

The date parameter is the update deadline—the final date that the user can update before the Exchange Server will prevent Outlook from working.

Once this is in place, Autodiscover checks this version number and compares it to the client version number. If they don’t match, a notification message is displayed on the notification bar and also in the backstage Office Account tab.

Notification bar: Outlook needs to be updated

Office Account Tab: Outlook needs to be updated

If the user continues to put off updating, as the deadline approaches, the call to action messages displayed in the notification bar and the Office Account tab escalate. After the deadline, if the Outlook client still hasn’t been updated, this notification is displayed:

Notification bar: Outlook needs to be updated now

Outlook Update vs. upgrade

If a major upgrade is available, the message notification and escalation are the same, except that the message reads "UPGRADE REQUIRED."

New MAPI over HTTP Outlook/Exchange transport protocol

If your enterprise has upgraded to Exchange Server 2013 SP1 and your user base is running Outlook 2013 SP1, then you’re well-positioned to use the newest communication mechanism, MAPI over HTTP.


  • Brings the Outlook and Exchange Server connection closer to the industry standard HTTP model and makes transport errors more discoverable and recovery easier.

  • Means faster reconnect times for users after device hibernation or moving from a wired network to a wireless or cellular network.

  • Maintains session context even if the user changes networks.

To implement MAPI over HTTP, you’ll need to:

  1. Upgrade all Outlook clients to Outlook 2013 SP1.

  2. Upgrade Client Access and Mailbox servers to Exchange Server 2013 SP1. For information about how to upgrade, see Upgrade Exchange Server 2013 to the Latest Cumulative Update or Service Pack.

  3. Configure Exchange Server 2013 SP1. Note that the MAPI over HTTP feature is disabled by default. Before enabling it, the Exchange Server admin will have to make sure that the prerequisites are met—like installing SP1 on various server roles and making sure that a digital certificate is in place. A digital certificate is needed because the MAPI over HTTP connection requires secure HTTP (HTTPS).

Coexistence of MAPI over HTTP and RPC over HTTP

While a mix of MAPI over HTTP and RPC over HTTP (the previous connection technology) is supported in the same Database Availability Group, we strongly recommend that the entire Exchange Server organization be upgraded to SP1 before you enable MAPI over HTTP. And here’s a good reason why: When a mailbox is moved from, or to, an Exchange Server computer that is configured for MAPI over HTTP, Autodiscover will notify Outlook that an Outlook profile update is needed in the registry. It’s a simple button click for the user, but may result in questions for you.

Your admin made a change, so you'll need to update


Outlook clients that are not MAPI over HTTP capable can still use Outlook Anywhere (RPC over HTTP) to access Exchange Server through a MAPI-enabled Client Access Server (CAS).

Temporarily disabling MAPI over HTTP for testing or troubleshooting

If you’ve successfully enabled MAPI over HTTP on both your Exchange Server 2013 and Outlook client, but then need to temporarily disable it for testing or troubleshooting, change this registry value on the Outlook client:


Value Name: MapiHttpDisabled


Value: 1

This simple client registry value change will prevent Outlook from advertising its MAPI over HTTP capability in the Autodiscover requests that are sent to the Exchange Server.


Be sure to remember to reset the MapiHttpDisabled value to 0 when you’re done troubleshooting.

Offline Outlook data files that are no longer associated with a profile or email account are automatically deleted

Outlook can potentially store large amounts of data in Outlook offline data (.ost) and Offline Address Book (.oab) files. In Outlook 2013 pre-SP1 builds, deleting a profile or an email account does not delete the .ost and .oab files—which could mean large, orphaned .ost and .oab files remain on the computer disk or device storage.

In Outlook 2013 SP1, new functionality deletes the .ost and .oab files that are associated with an email account or profile when that email account or profile is deleted—with a warning message just in case you want to keep the files or do a backup before deleting. Although devices running Windows RT may benefit most from this change, the new functionality is part of all Outlook 2013 SP1 versions, both for RT and for the desktop.

Abandoned email accounts or profiles aren't the only scenario in which .ost and .oab files will be deleted. If Outlook determines that an existing .ost or .oab file has become corrupted or is no longer usable, Outlook will delete the old .ost file before generating a new one.

This new functionality also applies to offline files that are located on network shares. And, if an Exchange email account is switched from Cached Exchange Mode to Online mode, the .ost and .oab files are still referenced in the profile—so, if the profile is deleted, the associated .ost and .oab files are also deleted.


You’ll have to reboot the client machine to see that the old data files have been deleted.

The user perspective—Outlook on smaller devices


This feature was actually introduced before Outlook 2013 SP1 but may have gone unnoticed by users, so we’re taking this opportunity to point it out.

With the big increase in smaller devices, suddenly all the great information that the Outlook user interface provides can look like TMI (too much information). To reduce the noise, Outlook 2013 SP1 enables users to switch between a full email header and a minimal email header in the reading pane. Here’s an example of a full email header.

Example of a full email header

If the user clicks the caret, the additional information disappears from view, revealing the minimal header shown here.

Example of a minimal email header

The minimal header gives the message content priority, reduces scrolling, and can save time while triaging email.

For developers—extensibility for Outlook mail apps in compose forms

With SP1, third-party developers can extend the mail- and calendar-compose experience through task pane mail apps in Outlook.

In Office 2013, Outlook could activate mail apps when the user viewed a message or appointment in a read form (in the Reading Pane or read inspector). Now, with SP1, Outlook can also activate mail apps in a compose form, when the user is authoring a message or appointment in an inline reply or compose inspector.

See also

What's new in Outlook 2013