Caution: The following procedure deletes any information that is not synchronized with the Exchange server, including your contacts' mail certificate.
Before emptying the cache, you may want to back up your Outlook information that is stored only locally on your computer.
Sometimes it’s something simple that can throw off Outlook.
If you’re having Outlook connectivity issues, then there’s a chance that Outlook is in Offline mode.
For more information, see Export or manually archive Outlook items.
So try to clear the offline items by following these steps: Resolution 2: Delete OST Files Outlook caches and stores email messages, calendar events and other items in Offline Storage Table (.ost) file.
You can also check the status of the Exchange server by contacting your Exchange server administrator.When the items in Outlook is mismatched with online version, the cached items may be corrupted.So try to clear the offline items by following these steps: Outlook caches and stores email messages, calendar events and other items in Offline Storage Table (.ost) file.Update 3/18/2014: The fix for this issue has been released and is a part of March 11 2014 update for Outlook 2013. We wanted to make certain that Exchange admins are aware of an Outlook issue which may impact your plans to move to Exchange Server 2013.As discussed in KB:2934750, Outlook 2013 customers who deployed client updates released in November and December of last year may experience a profile migration error post mailbox migration.When this occurs, it might not be possible to use normal Profile Repair options to restore connectivity.Older versions of Outlook, including Outlook 2013 the November and December updates will function normally.Summary: Learn about the two Exchange connectivity modes that you can use for Outlook 2013 deployments—Cached Exchange Mode and Online Mode.Audience: IT Professionals Decide which connectivity mode, Cached Exchange Mode or Online Mode, is appropriate for your environment.Many people have to connect to the Outlook Exchange Server to access their work emails.Occasionally Outlook has problems connecting to the server.