Should i run outlook in cached mode

You should user online mode when users have no persistent storage to which they can store their OST, such as VDI scenarios or on devices with limited storage capacity, such as tablets. You may also use online mode for extremely large mailboxes to improve overall performance, or where you do not want to risk having a local copy of the OST for compliance or other reasons.

I disagree with the general opinions about risks associated with using OST files. If you have a machine that leaves the physical security of your four walls, then you have a data risk no matter whether you use cached mode or online mode. Latency is really the most significant thing to consider when deciding between cached an online mode.

If you have high latency, you should use cached mode; if you have consistent and reliably low latency, online mode is okay. What is high and what is low? As a rule of thumb, I consider milliseconds to be the maximum latency for online mode.

If you are seeing client connections to the CAS server go over that consistently, you might want to switch to cached mode. That usually generates helpdesk calls, and nobody likes those. In the former, you can use a GPO to restrict the maximum size of the OST, as you may not need to cache the entire mailbox.

When it detects a smaller disk drive, Outlook and later will automatically reduce the OST size by reducing the number of days cached. For VDI, where persistent storage can be extremely expensive and sometimes even counter to the design intent, you have to make a tradeoff between space taken and performance. For Office or other hosted Exchange customers, the answer is easy — use cached mode. 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:. Outlook continues to synchronize the Outlook data with mobile devices, and some client-side rules might run.

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.

For a scenario where users' actual data throughput is slow, even though their network adapters report a fast connection, you can disable 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, you can also disable automatic switching to downloading only headers. When an Outlook account is configured to use Cached Exchange Mode, there's always a local copy of a user's Exchange mailbox ready in an offline data file. By default, the. When the user is online, the cached mailbox and OAB are periodically updated from Exchange Server in the background.

Any email messages the user drafted while offline are automatically sent when that user is back online. If a user upgrades from an earlier version of Outlook to Outlook and you previously configured Outlook for Cached Exchange Mode, those old Cached Exchange Mode settings are automatically applied, including a new synchronization control for shared mailboxes.

The default location for new. As an administrator, you can configure a different. If you do not specify a different. The Mail to keep offline slider in the Server Settings dialog box in Outlook has been updated to apply to shared folders and lets you set a smaller synchronization window, available by default with Cached Exchange Mode in Outlook The slider allows an Outlook user to limit the email messages that are locally synchronized in a Microsoft Outlook data file.

By default, if Cached Exchange Mode is enabled, Outlook caches email messages only from the last 12 months and removes anything older from the local cache for the PC.

These default settings depend on the device, with mobile devices having smaller default settings. The email messages that are removed from the local cache are still available for users to view, but they'll need to be connected to Exchange Server to view them. Users can view messages that were removed from the local cache by scrolling to the end of a message list in a folder and clicking the message Click here to view more on Microsoft Exchange.

Users can also change how much email to keep offline. You, the administrator, can change the default age or enforce the age of email messages that are removed from the local cache. Remember that customizing Cached Exchange Mode settings is optional. In the Account Name column, click the account you want to configure, and click Modify to display the Exchange Settings dialog box. By default, Cached Exchange Mode is disabled.

Right-click the policy object that you want, and click Edit. The Group Policy Management Editor window opens. In the Default location for OST files text box, enter the default location for.

For example:. You can define a new default location for both Personal Microsoft Outlook data files. Online Mode works well in environments where users have no persistent storage to which they can store their OST, such as VDI scenarios or on devices with limited storage capacity i. As the name states, a copy of your mailbox is saved on your computer, this provides quick access to your data and is frequently updated with the server that runs Microsoft Exchange.

By default, this mode is enabled whenever you add an Exchange or Office Account. The main purpose of this cache is to reduce network traffic, reduce the payload on the Exchange Server s and provide offline availability in-case you ever have network troubles — this cache, or.

Generally, your mailbox data includes mail, calendar, shared folders and additional mailboxes linked to your Exchange account. Depending on which mode and settings are enabled, by changing the amount of data to synchronise can affect the time it takes Outlook to open as well as the amount of storage space Outlook uses on your computer. Outlook reads and writes items into the.

Typically, latency might be higher and cached mode will accommodate this. Outlook: Online Mode vs. Cached Exchange Mode.