How To: Fix Outlook Sync Issues

Outlook is a very complicated application, but far and away the most common issues involve caching issues.

For clarity, this article is about the Outlook desktop application that comes on Windows computers that is installed along with Microsoft Office. This article is not about the web version of Office 365 or about mobile versions of Outlook.

In the background, Outlook communicates with servers to maintain a view of your email that resides on a collection of servers. In order for this process to be more responsive, Outlook uses a feature called caching. This involves storing remote data temporarily on the local computer so that it can look to the local files rather than the server for every transaction.

If the cache feature is disabled then you will receive frequent waiting periods while the network resources are verified and downloaded.

If the cache is corrupted – due to many possible reasons – then lots of odd behaviors can surface. Often new emails will not show in your mailbox, or emails you sent will not be seen in the sent mail, or some emails will show and others will not. The solution to this is to delete the cache and let Outlook recreate it.

To remedy Outlook caching issues, please follow the instructions below. These instructions were written specifically for Outlook 2016, but they should work for Outlook 2013 or Outlook 2010 as well.


1] Start Outlook
First, you will need to open Outlook and access your mailbox.

2] Click on File
Click on the File Menu to access the Info menu.
Screen shot of Outlook dialogue box

3] Account Settings – Account Settings
Select the option for Account Settings under the Account Settings drop-down menu.
Screen shot of Outlook dialogue box

4] Select Outlook Account and Click Change
Select your Outlook Exchange account (your @uconn.edu account) and click on the Change button.
Screen shot of Outlook dialogue box

5] Disable Caching
Uncheck the option for “Use Cached Exchange Mode.”
Screen shot of Outlook dialogue box

6] Exit Outlook
Close out of the menus and exit out of Outlook.

7] Re-Enable Caching
Go back to the “Change Account” settings through File – Account Settings – Account Settings – select account – click Change. Turn on the “Use Cached Exchange Mode” button. You may want to set the “Mail to keep offline” slider to “All,” otherwise older emails may be slower to search or access.
Screen shot of Outlook dialogue box

8] Exit Outlook
Again, close out of the menus and exit out of Outlook.

9] Open Outlook for Re-caching
When Outlook is opened again it will begin the process of re-caching the emails, calendars, tasks and so on. This process can take up to several hours, depending on how much data you have in the cloud.