How to Fix Cannot Open Default Email Folders on MS Exchange?

Microsoft Outlook application and Microsoft Exchange Server collaboratively creates an e- communication environment. MS Exchange Server stores mailboxes of all users in a single EDB file i.e. Exchange Database file. For each user mailbox, a separate profile is created that can be accessed through Outlook with differential credentials. Offline folder files or OST files are typically the exact replica of your mailbox folder in Exchange Server that is stored on user’s local system. This OST files will get synchronized with the Exchange Server mailbox every time you get connect with Mailbox Server. After proper synchronization, the OST file will get converted into PST file that is accessible with Outlook.

Outlook OST files are very susceptible to corruption and they can be easily get corrupted due to various internal and external causes. Many times, the OST files undergo issues due interruption during synchronization with Exchange Server database and the OST file becomes inaccessible with all its contents.

When you try to start MS Outlook, you may get the error message: “Cannot open your default email folders. The file*.ost is not an offline folder file.”

The two reasons that are responsible for this error message is as shown below:

  • The OST file is damaged or corrupted and cannot be recognized by Microsoft Outlook, so Outlook will report this error
  • When OST file becomes inaccessible i.e. user is unable to access the file with Microsoft Outlook, then the error might have occurred while synchronizing

There is free utility offered by Microsoft to resolve OST issues. This tool is known as OST Integrity Check tool (Scanost.exe). It is an in-built tool of Microsoft that can diagnose and repair synchronization issues. It performs some basic level of scanning and can be useful in restoring the OST file structure. This utility scans both your OST file on the Exchange Server mailbox, compare the items and folders in each file and tries to resolve synchronization issues.

Fix OST File Error by Using OST Integrity Check Tool (Scanost.Exe):

  • Quit Outlook if it is running.
  • Double-click on Scanost.exe, located at drive:\Program Files\Microsoft Office\OFFICE 12.
  • If you are having multiple profiles on Outlook, then the tool will ask you to select one. In the Profile Name list, click the profile that contains the required .ost file.
  • Select the Repair Error check box for automatically resolving inconsistencies found during the OST scanning. If the check box is not marked, the utility will only log the problems but not make the needed corrections.
  • Click Begin Scan.

After completing the process, your OST file will be repaired. However, in case log files show error that could not be resolved, you will have to create another OST file. The inaccessible data of OST file can be recovered by converting it into PST file format. There is no any inbuilt tool for converting the inaccessible OST file to PST file, so you need third party software. Although, a number of OST to PST email conversion tool are present on market, you are recommended to try Yodot OST to PST Converter utility. This software is capable of solving all possible minor and heavy OST corruptions on Windows PC.

OST to PST email conversion utility:

Yodot OST to PST Converter is email conversion software that uses advanced scanning techniques to efficiently convert OST files to PST files. This tool has the capability to resolve error “cannot open your default email folders” or “The file *.ost is not an offline folder file” that are occurred on Microsoft Outlook. This software is a read-only tool that doesn’t modifies the original OST file during conversion process, rather it reads source OST file and converts it into a new PST file. The conversion is very simple and you can also restore all your Emails, Contacts, Email attachments, Calendar items, tasks, journals, notes etc. after converting OST to PST file on Windows operating system.

Procedure for using Yodot OST to PST Converter:

  • Download and install Yodot OST to PST Converter software on your Windows computer
  • Launch the software either by using shortcut or by from start menu
  • In main screen you get two options i.e. “Open OST File“ and “Find OST File”
  • Select “Open OST File” if you know the exact location of OST file on your system
  • Else, select “Find OST File” if you don’t know the exact location of OST file on your system
  • In next screen you can browse for destination path to store the converted OST file
  • Click on “Convert” button to start conversion process
  • After conversion, you will receive a confirmation message like “OST file conversion completed”


  • Regularly update the anti-virus application to protect your OST files from virus or malware infections
  • Whenever you encounter this problem, you just check the email account for Exchange mailbox is disabled or deleted