To work with public folders offline, you need to use Cached Exchange Mode, which allows you to save a local copy of folders.
- In Outlook, expand the folder list, right-click the public folder that you want to work with offline, and choose Add to Favorites. Give a display name for the Favorites folder and click Add.
- Enable public folder Favorites for download:
Navigate to Tools > Account Settings. Double-click on Microsoft Exchange.
Outlook 2010/2013/2016:Navigate to File > Account Settings. Double-click on the email account.
- Navigate to More Settings > Advanced and select the option Download Public folder Favorites.
This creates a local copy of this public folder so you can work with it offline in Cached Exchange Mode.
Note: Cached Exchange Mode must be turned on to enable this feature.
Read the Knowledge Base article on How To Enable Cached Exchange Mode In Outlook for more information on using Cached Exchange Mode.
For additional details about Cached Exchange Mode, refer to the following Microsoft Knowledge Base article:
Turn On Cached Exchange Mode