.OST file Maintenance for Outlook 2007 and 2010

OST file Maintenance

Summary: This article describes how to repair or rebuild the .OST database to resolve synchronization problems in Microsoft Outlook 2007 and 2010 for Windows using Exchange.

If you are unable to synchronize your mailbox, calendar, or contacts with data on the server this may indicate your Outlook cache is corrupt. You can verify that data on the server is correct by using Outlook Web Access (http://xmail.clemson.edu) and comparing the data. The recommended action in these instances would be to rebuild your Outlook cache and resynchronize your Exchange data. Your Outlook cache is stored in an .ost file and is set by default for most of Clemson users for improved performance.

Outlook 2007 & 2010

Important information you should know.

The Outlook OST Integrity Checker tool (Scanost.exe) tool was removed from Microsoft Outlook 2010.

Microsoft previously recommended that you use the Scanost.exe tool for errors that occur with your offline Outlook Data File (.ost) or with synchronization issues. They now recommend that you delete your (.ost) File and that you let Outlook re-download the information from the server that is running Microsoft Exchange.

To Remove and Recreate your OST file:

OL OST Step 1Step 1: Exit Outlook.

In Control Panel, click or double-click Mail.

OL OST Step 2Step 2: The title bar of the Mail Setup dialog box contains the name of the current profile. Click E-mail Accounts..

If you need to select a different Profile other than the default, click Show Profiles instead, then select the profile name, and then click Properties. (then continue to step 3)

OL OST Step 3Step 3: On the E-mail tab, select the Exchange account, and then click Change.

OL OST Step 4Step 4: In the Change Account dialog window.

  1. Clear the Use Cached Exchange Mode check box.
  2. Then Click More Settings.


OL OST Step 5Step 5: On the Advanced tab, click Offline Folder File Settings.

OL OST Step 6Step 6: Click Disable Offline Use

Note: If you cannot click Disable Offline Use, this indicates the Use Cached Exchange Mode check box was not cleared in step 4. This check box must be cleared.

OL OST Step 7Step 7:, Then in the dialog box that appears, click Yes.

Step 8: Click OK.

OL OST Step 10Step 9: Under Cached Exchange Mode Settings section, select the Use Cached Exchange Mode check box and Download shared folders.

Then Click OK.

Step 11: click Next, and then click Finish.

Step 12: In the Account Settings and Mail Setup dialog boxes, click Close

The .OST Integrity Check tool, Outlook 2007

If you are using Outlook 2007 and would like to run the the OST Integrity Check too(Scanost.exe), it is located at:

drive:\Program Files\Microsoft Office\OFFICE12.

Repair errors by using Scanost.exe

  1. Exit Outlook if it is running.
  2. Double-click Scanost.exe, located at drive:\Program Files\Microsoft Office\OFFICE12.
  3. If you have set up Outlook to prompt for a profile, the tool will also prompt you for one. In the Profile Name list, click the profile that contains the .ost file that you want to check.

If you are prompted to Connect or Work Offline, click Connect.

  1. Select the options that you want.

To have the tool automatically resolve discrepancies that it finds during the scan, select the Repair Errors check box. If this check box is cleared, the tool will log the problems but not make the necessary corrections.

  1. Click Begin Scan.

If the scanost tool does not correct your issue, you will need to recreate your OST file. These instructions are the same for Outlook 2007 & 2010, and are contained in the Outlook 2007 & 2010 section above.

Backing up .OST data for re-import

Important information you should know.

Warning: the following section is provided in the extreme case that you have extensive data locally that needs to be pushed back to the server. It should only be used with extreme caution.

In the case that your offline Outlook Data File (.ost) has local data that is not present on the server, you can export the data to an Outlook Data File (.pst), and then you delete your (.ost). After the data is re-downloaded from the Exchange server, you can import the (.pst) into the new (.ost). During the import, you MUST exclude any duplicate data from the (.pst) to prevent their inclusion in your Mailbox.

To import the (.pst) into the new (.ost), follow these steps:
  1. On the File tab, click Open, and then click Import.
  2. Select Import from another program or file, and then click Next.
  3. Select Outlook data file (.pst), and then click Next.
  4. Click Browse, and then locate the PST file that you exported.
  5. Select Do not import duplicates, and then click Next.
  6. Under Select destination folder, click a folder to which you want to import the information, and then click Next.
  7. 7.Click Finish.

Ref docs: 983036 & HA010354964

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