Outlook 2016 updating cached headers imap
Outlook 2013 added a new feature, Sync Slider, that limits the amount of mail synced with Outlook, in an effort to limit the size of the offline cache file used by Exchange or IMAP mailboxes.
In Outlook 2013, only the account mailbox is affected by the sync slider, the setting does not apply to shared or delegated mailboxes.
Slide the control to determine how much older email is stored offline.
For Outlook 2013, Exchange accounts can sync as little as 1 month, while Outlook 2016 can sync as little as 3 days of messages.
To view mail that is not synced down, click on "Click here to view more on Microsoft Exchange" at the bottom of the message list.
Users will need to use Instant Search or OWA to view older messages.Here is a list of default Outlook add-ins: This page contains a List of all default Outlook Add-ins, plus other add-ins you might encounter.In addition, other third-party applications can add their own Outlook add-ins.To do this, right click on the folder and choose Properties, Synchronization tab. You'll need to repeat this on each folder where you want to limit what syncs.
Because only Public Folder Favorites sync, removing folders not needed offline from the Public Folder Favorites list will help to reduce the size of the cache.In Outlook 2016, the sync slider also limits the age of mail sync in shared mailboxes that are cached.