Issues when you synchronize your Exchange Server mailbox with your .ost file in Outlook

  • Article
  • iii minutes to read
  • Applies to:
    Outlook 2019, Outlook 2016, Outlook 2013, Outlook for Microsoft 365

Original KB number: 842284

When you try to synchronize a Microsoft Exchange Server mailbox with an Offline Outlook Data File (.ost), the synchronization fails, and you experience any of the following issues:

  • Folders in Microsoft Outlook are not updated.
  • Email messages are bachelor in Outlook on the web (OWA) only not in Outlook.
  • You see a different message count in Outlook and OWA.
  • New e-mail letters are not downloaded in Outlook.

These issues occur if either the .ost file or the Exchange Server back up file is damaged. This article provides guidance to troubleshoot and resolve these issues.

Determine whether offline folders are beingness synchronized

Follow these steps in Outlook:

  1. Correct-click an offline folder, and select Properties.

  2. Select the Synchronization tab.

    Annotation

    If you don't see the Synchronization tab, this indicates that you didn't gear up up your profile to use offline folders.

  3. Under Statistics for this folder, verify the settings in the following fields:

    • Final Synchronized on
    • Server folder contains
    • Offline folder contains

    Screenshot shows the statistics for this folder under the Synchronization tab.

If synchronization is working correctly, the number of items in the Server folder contains field and the Offline folder contains field volition be the same.

Synchronize the folders again

After you check the offline folder settings, utilise 1 of the following methods to synchronize the folders again.

Manual synchronization

  1. Select the folder that you desire to synchronize.
  2. On the Outlook ribbon, select Send/Receive, and and then select Update Folder to synchronize one offline folder, or select Ship/Receive All Folders to synchronize all offline folders.

When the synchronization procedure starts, yous'll see a synchronization status bulletin in the lower-correct part of the screen. If you have many items in the mailbox, and y'all haven't synchronized the offline folders for a while, the synchronization process might take more than 30 minutes.

Automatic synchronization

To synchronize all offline folders automatically every time that yous're online and every time that you exit Outlook, follow these steps:

  1. On the File tab, select Options.
  2. In the Outlook Options dialog box, select Advanced.
  3. In the Send and receive section, select the Send immediately when connected bank check box.
  4. Select Transport/Receive.
  5. In the Send/Receive Groups dialog box, make sure that the Perform an automatic send/receive when exiting bank check box is selected, and then select Close.
  6. select OK.

Create an .ost file

If all the folders except the Inbox folder are synchronized, or if you're not able to synchronize the folders, you might take a damaged .ost file. To gear up the issue, create a new .ost file. Follow the steps in How to rebuild the OST file. Then, synchronize the offline folders again.

Replace a damaged Exchange Server support file

If you're still not able to restore offline folder synchronization, the Microsoft Substitution Server service support file might be damaged. To replace the damaged service support file, you must either remove or rename the file, and then supplant the removed or renamed file with the original service support file.

Remove or rename the Commutation Server service support file

Follow these steps:

  1. Open File Explorer.

  2. Locate C:\Program Files(x86)\Microsoft Office\root\Office16 or C:\Program Files\Microsoft Office\root\Office16.

    Note

    The folder path to the EMSMDB32.dll file will vary, depending on the version and flake-value of the Part product installed.

  3. Right-click the EMSMDB32.dll file, select Rename, and and then add the .old filename extension. For example, EMSMDB32.dll.old.

Replace the Exchange Server service support file

To supervene upon the support file that you renamed in the original media, follow these steps:

  1. Right-click Beginning, and select Apps and Features on the pop-upwardly menu.

  2. Select the Microsoft Office product that yous want to repair, so select Modify.

  3. Depending on whether your copy of Office is a Click-to-run-based or .msi-based installation, yous'll run into the following options to go along with the repair. Follow the steps for your installation type.

    Click-to-run MSI
    In the How would you like to repair your Office Programs window, select Online Repair > Repair to brand sure that everything gets fixed. (The Quick Repair pick is faster, merely information technology just replaces corrupted files.) In the Change your installation window, select Repair, and so select Continue.

  4. Synchronize the offline folders.

For more information, run into Repair an Role application.