Synchronization Issue of Outlook & OWA

When Outlook or Outlook Web Access (OWA) doesn't synchronize with Exchange Server properly, there are some indications of it.

  • The number of emails in folders of OWA and Outlook 2003/2007/2010 are differ
  • In case you have disabled the cached mode, all things work smoothly but Outlook can create trouble
  • Error message has come while synchronizing OST files with exchange server
  • Once the synchronization process is over, it may possible that some folders from Exchange mailbox and OST file go missing

For Outlook 2003/2007

Microsoft provides free OST integrity check program called Scanost.exe.It fixes the issue efficiently. To repair the problem, all you need to:

Run Scanost.exe (OST integrity check) tool to learn about any inconsistency in the .OST file. The utility installs automatically while you install Outlook.

Check out the location of the tool.

  1. Double click the Scanost.exe and enter the Profile Name which holds the OST file. There are two options come forth- Connector Work Offline. Select "Connect".
  2. In case you would like to the utility to automatically fix the difference during the time of scanning OST, activate "Repair Errors" option and click "Begin Scan".

For Outlook 2010

In Outlook 2010, the Scanost.exe tool is not provided. So if there is any issue come up with a particular folder, resynchronize the folder is recommended.

  • Right click on the targeted OST folder that you wish to re-synchronize, now select "Properties" from the drop down menu
  • Press Clear Offline Itemsand then OK
  • Now in the application ribbon, choose send/receivetab to start the process
  • Press Update Folder

If it doesn't work, it means it's time to re-build OST file- delete whole data from folder and begin installation from MS Exchange server

Process of Re-Build an OST File

Delete the existing OST file which you would like to re-build and then rename that OST file

  1. In order to find out the targeted OST file, visit the Start menu and in the field box provide the following path
    1. Windows XP: C:Documents and Settings<alias>Local SettingsApplication DataMicrosoftOutlook
    2. Windows Vista/7: C:Users<alias>AppDataLocalMicrosoftOutlook
  2. In case, folders are now showing, you need to unhide them. For this
    1. Open My Computer and from Tools/organizemenu, take cursor to Folder Options/Folder and Search Options
    2. In the View box, disable the optionHide Extension for Known File Types
  3. Automatically, the cache copy of Exchange server will be saved to Outlook .OST. In case it is already created, the Outlook will create suffix of the file like Outlook 1.OST. You are free to give a unique name to it.
  4. In case it shows "File in Use" error, confirm that Outlook.exe and Winword.exe processes are not running at the background. Confirm about this through Task Manager. Open the Task Manager and see whether they are running. If yes, select and click on "End Task"
  5. As the renaming process is over, restart Outlook. You get the message "Preparing for First Use". Wait because the synchronization process is going on. The timing of synchronization is depending on the OST file size.
  6. When mailbox is synced with OST file, confirm that the problem is solved or not. If it is not resolved, it means the problem is not associated with the OST file.