Mailbox data is only cached in memory and never written to disk. Online Mode works by using information directly from the server as the name implies, it requires a connection. The second type of Exchange connection mode is Online Mode. While Cached Exchange Mode is the default and recommended mode, there are some known issues with this mode, including synchronization delays with shared items and address book updates see Known issues with Cached Exchange Mode. Users who have high-latency connections (greater than 500 ms) to the Exchange servers.Users who frequently work offline or without connectivity.Portable computer users who frequently move in and out of connectivity.When the user is online, the cached mailbox and OAB are periodically updated from the Exchange Server in the background.Ĭached Exchange Mode is especially valuable for: Any email messages the user drafted while offline are automatically sent when that user is back online. If a user is offline and using Outlook, the program works from this local copy and with the Offline Address Book (OAB).

After messages have been pulled over the network one time, subsequent access to those messages does not cause additional network traffic. It's also designed to help insulate users from network latency and connectivity issues while they are using Outlook.īy caching users' mailboxes to their computers, Outlook no longer depends on continuous network connectivity for access to user information. ost file) on the user's computer, together with an Offline Address Book (OAB).Ĭached Exchange Mode's purpose is to provide a seamless online and offline Outlook experience. When an Exchange account in Outlook is configured to use Cached Exchange Mode, Outlook works from a local copy of the user's Exchange mailbox that is stored in an offline data file (. Outlook for Mac desktop versions (including 2016) support only Cached Exchange Mode.Ĭached Exchange Mode is the default and recommended configuration for most scenarios except those mentioned under When to use Online Mode.See Configure Exchange Online with Outlook or Windows Mail.

Outlook 2016 known issues