Plan a Cached Exchange Mode deployment in Outlook 2013

 

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

Summary: Plan a Cached Exchange Mode deployment for Outlook 2013.

Audience: IT Professionals

Outlook 2013 provides two basic connectivity modes when you are connected to an Exchange Server computer: Cached Exchange Mode, and Online Mode. Cached Exchange Mode is the premier and recommended configuration in Outlook 2013 in all circumstances, except those that are specifically called out in When to use Online Mode, in the article Choose between Cached Exchange Mode and Online Mode for Outlook 2013.

This article describes important Cached Exchange Mode features and talks about some planning considerations for deployments in Outlook 2013. You’ll also find information about the sync slider and the new Outlook compressed data file (.ost) format here.

In this article:

• Synchronization, disk space, and performance considerations for Cached Exchange Mode

• Managing Outlook behavior for perceived slow connections

• Options for staging a Cached Exchange Mode deployment

• Upgrading current Cached Exchange Mode users to Outlook 2013

• Cached Exchange Mode settings for Outlook 2013

Synchronization, disk space, and performance considerations for Cached Exchange Mode

In some cases, you can improve the performance of Cached Exchange Mode for your whole organization or for a group of users—for example, users who work remotely.

Synchronization changes in Outlook 2013

In Outlook 2013, two new features are available with Cached Exchange Mode: Exchange Fast Access and sync slider.

Exchange Fast Access combines the instant-access of Online Mode with the offline capabilities and syncing robustness of Cached Exchange Mode, specifically in scenarios when syncing data locally would take enough time to be noticed by the user (for example, initial sync, resume, or returning from vacation). When you first start Outlook 2013, you will immediately see your most recent email messages and a completely up-to-date calendar. Outlook 2013 caches items in the background to prepare users for offline use without affecting their experience.

Sync Slider allows an Outlook 2013 user to limit the email messages that are synchronized locally in an Outlook data file (.ost). By default, if Cached Exchange Mode is enabled, Outlook 2013 will only cache email messages from the last 12 months and remove anything older than 12 months from the local cache. Users can view messages that were removed from the local cache by scrolling to the end of an email list in a folder and choosing the message Click here to view more on Microsoft Exchange. Users can also change how many email messages are kept offline. You, as the IT Administrator, can change the default age or enforce the age of email messages that are removed from the local cache by using Group Policy or the Office Customization Tool to set Cached Exchange Mode Sync Settings. For more information, see Configuring Cached Exchange Mode later in this article.

Outlook data file (.ost) recommendations

If you are moving from using Online Mode to Cached Exchange Mode as part of the deployment of Outlook 2013, be aware that users' local .ost files can increase 50 percent to 80 percent over the size of the mailbox that is reported in Exchange Server. The format that Outlook uses to store data locally for Cached Exchange Mode is less space-efficient than the server data file format. This means that more disk space is used when mailboxes are downloaded to provide a local copy for Cached Exchange Mode.

By default, when you install Outlook 2013 and enable Cached Exchange Mode, a new compressed version of the Outlook data file (.ost) is created. This new compressed version of the .ost is up to 40% smaller than the size of the .ost files that were created in earlier versions of Outlook.

If you must keep Outlook 2013 from creating a new compressed Outlook data file (.ost), use the Outlook Group Policy template (Outlk15.admx) to enable the Do not create new OST file on upgrade policy. Find this setting under User Configuration\Administrative Templates\Microsoft Outlook 2013\Account Settings\Exchange.

The maximum size for the new compressed format of the .ost files is configurable. The default is 50 GB of data storage. Make sure that users' .ost files are located in a folder that has sufficient disk space to accommodate users' mailboxes. For example, if users' hard disk drives are partitioned to use a smaller drive for system programs (the system drive is the default location for the folder that contains the .ost file), for the location of user’s .ost files, specify another drive and folder (other than the default location) that has more disk space.

• For more information about how to deploy .ost files to a location other than the default location, see To configure a default .ost location by using Group Policy in Configure Cached Exchange Mode in Outlook 2013.

• For more information about how to configure the Unicode .ost file size, see How to configure the size limit for both (.pst) and (.ost) files in Outlook. And if you ever need to reduce the size of your Outlook 2010 or Outlook 2013 .pst file, you can export data from that .pst file to another .pst file.

Managing performance issues in Outlook

Most users find that Cached Exchange Mode performs faster than online mode. However, several factors can influence a user's perception of Cached Exchange Mode performance, like hard disk size and speed, CPU speed, .ost file size, and the expected level of performance.

For troubleshooting tips about diagnosing and addressing performance issues in Outlook, see How to troubleshoot performance issues in Outlook and Performance tips for deploying Outlook 2007.

Managing Outlook folder sharing

By default, when Cached Exchange Mode is enabled in Outlook 2013 and Outlook 2010, shared mail and non-mail folders that users access in other mailboxes, are downloaded and cached in the user's local .ost file. This behavior differs from Outlook 2007 in which only shared non-mail folders are cached by default. For example, if a coworker 1 shares a calendar with coworker 2 and coworker 2 opens it, Outlook 2013 starts caching the folder locally so that coworker 2 has offline access to the folder and is insulated from potential network issues. Similarly, if a manager delegates access to his or her Inbox to a team member, when the team member accesses the folder, Outlook 2013 also starts caching the Inbox folder locally.

Cached folders enable offline access and can provide a much more reliable experience on slow or unreliable networks. But be aware that cached folders do take a little more time to populate at first; more data is synchronized so the local .ost file size increases; and in scenarios that have slow connections or where the user is offline, the folder is not current until the latest changes are synchronized and downloaded.

You can disable caching of all shared folders for profiles that have Cached Exchange Mode enabled. To do this, configure the Download shared non-mail folders option in the Office Customization Tool (OCT) when you customize your Cached Exchange Mode deployment. Note that this setting applies to both mail and non-mail folders in Outlook 2013.

If you want to disable caching of shared mail folders (like a delegated Inbox) but not shared non-mail folders (like Calendar), see By default, shared mail folders are downloaded in Cached mode in Outlook 2010.

For more information about how to change these settings, see Configuring Cached Exchange Mode later in this article and Configure Cached Exchange Mode in Outlook 2013 for step by step instructions.

Public Folder Favorites considerations

You can configure Cached Exchange Mode to download and synchronize the public folders that are included in users' Favorites folders for Outlook Public Folders. By default, Public Folder Favorites are not synchronized. However, you might want to enable this option if your organization uses public folders extensively. You can configure an option to download Public Folder Favorites in the .ost when you customize your Cached Exchange Mode deployment.

If users' Public Folders Favorites folders include large public folders, their .ost files can also become large. This can affect Outlook performance in Cached Exchange Mode. Before you configure Cached Exchange Mode to enable this option, make sure that users are selective about the public folders that are included in their Public Folder Favorites. Also, make sure that users' .ost files are large enough, and are in folders that have sufficient disk space to accommodate the additional storage requirements for the public folder downloads.

As an alternative to Public Folders, consider Site Mailboxes. Site mailboxes improve collaboration and user productivity by allowing access to both SharePoint 2013 documents and Exchange email that are in the same client interface. A site mailbox consists of SharePoint 2013 site membership (owners and members), shared storage through an Exchange Server 2013 mailbox for email messages and a SharePoint 2013 site for documents, and a management interface that addresses provisioning and life-cycle needs. SharePoint 2013 documents that are viewed in the site mailbox are stored only on SharePoint 2013.

Site mailboxes require Exchange Server 2013 and SharePoint Server 2013 integration and configuration. For more information, see Site mailboxes in the new Office and Configure site mailboxes in SharePoint Server 2013.

Managing Outlook behavior for perceived slow connections

Outlook is configured to determine a user's connection speed by checking the network adapter speed on the user's computer (supplied by the operating system). If the reported network adapter speed is 128 KB or lower, the connection is defined as a slow connection.

When a slow connection to an Exchange Server computer is detected, Outlook helps users have a better experience if they reduce the less-important information that is synchronized with the Exchange Server computer. Outlook makes the following changes to synchronization behavior for slow connections:

• Switches to downloading only headers.

• Does not download the Offline Address Book or OAB updates.

• Downloads the body of an item and associated attachments only when it is requested by the user.

Outlook continues to synchronize the Outlook data with mobile devices, and some client-side rules might run.

Note

We recommend that you do not synchronize mobile devices when the Cached Exchange Download only headers setting is enabled. When you synchronize a mobile device by using ActiveSync, for example, full items are downloaded in Outlook, and the synchronization process is less efficient than it is during regular Outlook synchronization to users' computers.

The Download only headers setting for synchronization is designed for Outlook users who have dial-up connections or cellular wireless connections, to minimize network traffic when there is a slow or expensive connection.

Under some circumstances, the network adapter speed might not accurately reflect data throughput for users. For example, if a user's computer is connected to a local area network (LAN) for fast access to local file servers, the network adapter speed is reported as fast because the user is connected to a LAN. However, the user's access to other locations on an organization's network that include the Exchange Server computer might use a slow link, such as an ISDN connection. For such a scenario, where users' actual data throughput is slow, even though their network adapters report a fast connection, you can configure an option to change or lock down the behavior of Outlook. You can do this, for example, by disabling automatic switching to downloading only headers by using the Group Policy option, Disallow On Slow Connections Only Download Headers. Similarly, there might be connections that Outlook has determined are slow but which provide high data throughput to users. In this case, youcan also disable automatic switching to downloading only headers.

You can configure the On slow connections, download only headers option in the OCT, or lock down the option by using Group Policy to set Disallow On Slow Connections Only Download Headers. For more information about how to customize this setting, see Configuring Cached Exchange Mode later in this article or Configure Cached Exchange Mode in Outlook 2013 for step by step instructions.

Options for staging a Cached Exchange Mode deployment

If you plan to upgrade a large group of users from an Online Mode deployment of Outlook to Outlook 2013 with Cached Exchange Mode enabled, stage the rollout over a period of time. A staged rollout helps your organization's Exchange Server computers manage the requirements of creating or updating users' .ost files.

Warning

If most user accounts are updated to use Cached Exchange Mode at the same time and then start Outlook at the same time (for example, on a Monday morning after a weekend upgrade), the Exchange Server computers may have significant performance issues—so a staged approach is preferable.

The following scenarios include examples of how you can deploy Cached Exchange Mode to avoid a large initial performance effect on the Exchange Server computers and, in some cases, minimize the time users spend waiting for the initial synchronization:

• Provide seed .ost files to remote users, and then deploy Cached Exchange Mode after users have installed those seed .ost files.   If most users in your organization do not currently have .ost files or are not using Cached Exchange Mode, you can deploy Outlook 2013 with Cached Exchange Mode disabled. Then, before the date that you plan to deploy Cached Exchange Mode, you provide to each user an initial, or seed, .ost file that has a snapshot of the user's mailbox. For example, you can provide or mail to the user a CD that contains the file together with installation instructions. You might also want to provide a recent version of your organization's Office Address Book (OAB) that has full details. Confirm that they have installed the files.

  After confirming that the users have installed the seed .ost file, update your Outlook deployment to use Cached Exchange Mode. Exchange Server updates users' existing (seeded) .ost files. There is much less data to synchronize than there would be if you create a new .ost file and OAB for each user. Creating individual CDs for each user's .ost file can be time-consuming. Therefore, this seed-file deployment option might be most useful for select groups of remote users who would otherwise spend lots of time waiting for the initial mailbox and OAB synchronization, perhaps at a high cost, depending on the remote connection scenario.

  For more information about how to create initial .ost files, see Providing an initial OST file for an Outlook Cached Exchange Mode deployment.

• Deploy Outlook with Cached Exchange Mode to groups of users over time.   You can balance the workload on the Exchange Server computers and the local area network by upgrading groups of users to Cached Exchange Mode over time. By rolling out the new feature in stages, you can reduce the network traffic and server-intensive work of populating .ost files that have users' mailbox items and downloading the OAB.

  The way that you create and deploy Cached Exchange Mode to groups of users depends on your organization's usual deployment methods. For example, you might create groups of users in Microsoft System Center Configuration Manager to which you deploy a System Center Configuration Manager package that updates Outlook to use Cached Exchange Mode. You deploy that package to each group over time. To balance the load as much as you can, choose groups of users whose accounts are spread across groups of Exchange Server computers.

Upgrading current Cached Exchange Mode users to Outlook 2013

The process of upgrading users to Outlook 2013 when Cached Exchange Mode is already enabled in Office Outlook 2003, Outlook 2007, or Outlook 2010, is straightforward. If you do not change Cached Exchange Mode settings, the same settings are kept for Outlook 2013.

However, by default, when Outlook 2013 is installed and Cached Exchange Mode is enabled, a new compressed version of the Outlook data file (.ost) is created. This new compressed version of the .ost is up to 40% smaller than the size of the .ost files that were created in earlier versions of Outlook. If you are upgrading from an earlier version of Outlook that had Cached Exchange Mode enabled, the earlier version of the .ost file is kept and, if it is necessary, can be opened by Outlook 2013. If you must keep Outlook 2013 from creating a new compressed Outlook data file (.ost), use the Outlook Group Policy template (Outlk15.admx) to enable the Do not create new OST file on upgrade policy. For more information, see Configuring Cached Exchange Mode later in this article.

Also, be aware that in Outlook 2013, by default, shared mail and non-mail folders that users access in other mailboxes are downloaded and cached in the user’s local .ost file when Cached Exchange Mode is enabled. This behavior differs from Outlook 2007 in which only shared non-mail folders are cached by default. Therefore, when a user's existing Office Outlook 2003 or Outlook 2007 profile has Cached Exchange Mode enabled and that profile is upgraded to Outlook 2013, shared mail and non-mail folders are downloaded when the user accesses them. This can be problematic if your organization uses shared folders extensively and if you have .ost files that are close to the file limit (2 GB for ANSI .ost files and 20 GB by default for Unicode or compressed .ost files). When these factors are both present, you may experience performance issues and other problems if you download shared folders. For more information about file size limits, see The file size limits of .pst and .ost files are larger in Outlook 2010.

For new Outlook 2013 profiles or for upgrading existing Office Outlook 2003, Outlook 2007, or Outlook 2010 profiles, you can use the OCT or Group Policy to disable the download shared folder option and therefore help prevent problems that involve downloading shared folders. Be aware that the setting Download non-mail shared folders applies to both mail and non-mail folders in Outlook 2013.

If you want to disable the caching of shared mail folders (such as a delegated Inbox) but non shared non-mail folders (such as Calendar), see By default, shared mail folders are downloaded in Cached mode in Outlook 2010.

In addition, be aware that caching for shared folders works differently from other caching for Cached Exchange Mode. For shared folders, replication to the local .ost file starts only when the user chooses the shared folder. After a user starts caching for the folder by choosing (clicking) it, Outlook updates the folder exactly like other Outlook folders that are synchronized in Cached Exchange Mode. However, if the user does not go to the folder at least one time every 45 days (the default value), the locally cached data for the folder is removed from the .ost file and will not be downloaded until the user chooses on the folder again.

To configure the number of days when cached shared data is removed from the .ost file, you can configure the Synchronizing data in shared folders option in the OCT or Group Policy. For more information, see Configuring Cached Exchange Mode later in this article or see Configure Cached Exchange Mode in Outlook 2013 for step by step instructions.

Cached Exchange Mode settings for Outlook 2013

You can lock down the settings to customize Cached Exchange Mode by using the Outlook Group Policy Administrative template (Outlk15.admx). Or, you can configure default settings by using the Office Customization Tool (OCT), in which case users can change the settings.

By using Group Policy, you can help prevent users from enabling Cached Exchange Mode in Outlook 2013, and you can enforce download options for Cached Exchange Mode or configure other Cached Exchange Mode options. For example, you can specify the default times between Exchange Server synchronizations when data changes on an Exchange Server computer or on the client computer.

For steps to lock down settings by using Group Policy, see Configure Cached Exchange Mode in Outlook 2013.

The following table shows some settings that you can configure for Cached Exchange Mode. In Group Policy, you can find the settings under User Configuration\Administrative Templates\Microsoft Outlook 2013\Account Settings\Exchange\Cached Exchange Mode. The OCT settings are in corresponding locations on the Modify user settings page of the OCT.

Cached Exchange Mode settings

Setting name	Registry path and value name	Description
Cached Exchange Mode Sync Settings	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\cached mode!syncwindowsetting OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\cached mode!syncwindowsetting	Enable to configure how much user email that Outlook synchronizes locally by date of message. To allow all email messages regardless of date to synchronize to users’ local mailbox cache, enable and select All from the list. By default, if you do not configure this setting, Outlook synchronizes email messages sent or received in the last 12 months to users’ local mailbox cache (.ost).
Disable Exchange Fast Access	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\hybrid!localcaching OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\ hybrid!localcaching	Enable setting to turn off Exchange Fast Access. This forces user accounts to access data from the local cache.
Disallow Download Full Items	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!nofullitems OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\ outlook\cached mode!nofullitems	Enable to turn off the Download Full Items option in Outlook. To find this option, choose the Send/Receive tab, and then choose Download Preferences.
Disallow Download Headers	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!noheaders OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\ outlook\cached mode!noheaders	Enable to turn off the Download Headers option in Outlook. To find this option, choose the Send/Receive tab.
Disallow Download Headers then Full Items	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!nodrizzle OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\ outlook\cached mode!nodrizzle	Enable to turn off the Download Headers then Full Items option in Outlook. To find this option, choose the Send/Receive tab, and then choose Download Preferences.
Disallow On Slow Connections Only Download Headers	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!noslowheaders OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\cached mode!noslowheaders	Enable to turn off the On Slow Connections Download Only Headers option in Outlook. To find this option, choose the Send/Receive tab, and then choose Download Preferences.
Download Public Folder Favorites	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!syncpffav OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\cached mode!syncpffav	Enable to synchronize Public Folder Favorites in Cached Exchange Mode.
Download shared non-mail folders	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!downloadsharedfolders OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\cached mode!downloadsharedfolders	Enable to synchronize shared non-mail folders in Cached Exchange Mode.
Use Cached Exchange Mode for new and existing Outlook profile	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\ outlook\cached mode!enable OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\cached mode!enable	Enable to configure new and existing Outlook profiles to use Cached Exchange Mode. Disable to configure new and existing Outlook profiles to use Online Mode.

The following table shows some additional settings that you can configure for Exchange connectivity. In Group Policy, you can find the settings under User Configuration\Administrative Templates\Microsoft Outlook 2013\Account Settings\Exchange. The OCT settings are in corresponding locations on the Modify user settings page of the OCT.

Exchange connectivity settings

Setting name	Registry path and value name	Description
Automatically configure profile based on Active Directory Primary SMTP address	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\autodiscover!zeroconfigexchange OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\autodiscover!zeroconfigexchange	Enable to prevent users from changing the SMTP e-mail address that is used to set up a new account from the one retrieved from Active Directory.
Configure Outlook Anywhere user interface options	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\rpc!enablerpctunnelingui OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\rpc!enablerpctunnelingui	Enable to let users view and change user interface (UI) options for Outlook Anywhere.
Do not allow an OST file to be created	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\ost!noost OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\ost!noost	Enable to prevent offline folder use.
Do not create new OST file on upgrade	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\ost!donotcreatenewostonupgrade OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\ost!donotcreatenewostonupgrade	Enable to force Outlook 2013 to use the existing .ost file that was created by an earlier version of Outlook. If you disable or do not configure this setting (recommended), a new .ost file is created when you upgrade to Outlook 2013.
Set maximum number of Exchange accounts per profile	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\exchange!maxnumexchange OCT registry path: HKEY_CURRENT_USER\software\microsoft\exchange!maxnumexchange	Enable to set the maximum number of Exchange accounts that are allowed per Outlook profile.
Synchronizing data in shared folders	Group Policy registry path: HKEY_CURRENT_USER\software\policies\microsoft\office\15.0\outlook\cached mode!sharedfolderageoutdays OCT registry path: HKEY_CURRENT_USER\software\microsoft\office\15.0\outlook\cached mode!sharedfolderageoutdays	Enable to control the number of days that elapses without a user accessing an Outlook folder before Outlook stops synchronizing the folder with Exchange.

See also

Choose between Cached Exchange Mode and Online Mode for Outlook 2013
Configure Cached Exchange Mode in Outlook 2013

Plan to automatically configure user accounts in Outlook 2010