Difference between Cached Exchange Mode and Online Mode

Cached Exchange Mode

By locally storing the user's mailbox and the Offline Address Book, Cached Exchange Mode offers users a smooth online and offline Outlook experience.

Users' default option of Cached Exchange Mode means that Outlook no longer needs constant network connectivity to access user data.

When a user is connected, Outlook automatically refreshes users' mailboxes to keep them current. The user can still access the most recent email data even after disconnecting from the network, for instance, if they are travelling somewhere without internet connectivity.

Cached Exchange Mode is the preferred configuration in Outlook 2016 and is useful in the following situations:

• Users who frequently move in and out of connectivity.
• Users who frequently work without connectivity or offline.
• Users who have high-latency connections (greater than 500 ms) to Exchange Server.

Visit here to Enable Cached Exchange Mode. – BEMO Docs (bemopro.com)

Online Mode

Since online more uses data directly from the server, it relies on a connection.

Mailbox data is never written to disc, it is only cached in memory.

In the following scenarios, online mode is helpful:

• Situations like those at a kiosk, where a single computer is used by numerous people accessing various Outlook accounts, where the delay to download email messages to a local cache is not ideal.
• Places that are highly regulated or secure and where local data storage is risky.
• Mailboxes with a lot of content on PCs without enough hard drive space to save a local copy of the mailbox.

Managing Outlook performance problems

Most users discover that Cached Exchange Mode performs quicker than online mode.

However, their are a number of variables, like hard disc size and speed, CPU speed, file size, and the expected degree of performance which might affect a user's perception of Cached Exchange Mode performance.