How to restore your Outlook mailbox on Exchange Server in the event of OST corruption?

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November 22, 2012

OST file is created by MS Exchange Server in a local Windows Server. It is created in the same drive location of your Outlook PST files. When link between MS Outlook and Exchange mail server could not be established due to various reasons, Outlook mailboxes of mail server are saved in Offline folders or OST files. Each OST file contains a single Outlook user mailbox and allows a user to access emails in offline mode.

Corruption issues of OST file

When MS Outlook reconnects with MS Exchange Server, changes saved in an OST file get transferred into Outlook PST file. However, long disruption of internet services on MS Exchange Server leads to OST file corruption. Corrupt OST files fail to synchronize with a mail server and as a result, outlook users cannot use their mail accounts on that server. You’ll see various error messages on your computer screen in the event of OST corruption:

  • Unable to expand folder
  • Unable to expand folder
  • Errors have been detected in the File Outlook.OST
  • Outlook.OST is in use and could not be accessed

Inbuilt data recovery options

If your computer system is running on Windows XP, then you can create a new Outlook profile for your Exchange mailbox:

  • Click on Start> Control Panel>Mail
  • Press “Show Profiles” button to view the existing Outlook profile
  • Remove all existing Outlook profiles from the display box
  • Press “Add” to create new Outlook user profile
  • Type the new Outlook profile name and click “Ok”
  • Tick on “Manually Configure server settings or additional server types” box and press “Next” button
  • Select “Microsoft Exchange Server” email service
  • Type Exchange Server address and your user name
  • Uncheck the “Use Cached mode” box and press “Next” to make a new Outlook profile
  • Restart your Outlook mailbox

With this step, you can access your Outlook mailbox on Exchange Server after internet services resumes. However, data saved by Outlook user during offline period will not appear in your new Outlook mailbox.

Another inbuilt option is scanpst.exe that can fix minor corruption issues of OST as well as PST files. This inbox repair utility is located in the local MS Office folder of your system. You can find the tool from Windows Search file and folder box.

You must use external OST recovery software in the following conditions:

  • Badly damaged Hard disk
  • Crash of MS Exchange

OST to PST conversion tool

OST to PST conversion software can fix both minor and severe corruption levels of OST folders. It recovers and restores inaccessible, deleted or damaged Outlook profiles from the corrupt OST files. Recovered Outlook mailbox data is saved by this utility in PST files.

With the help of OST to PST conversion tool, one can quickly retrieve mailbox folders such as inbox, sent items, deleted items, drafts, journals and contacts from corrupt OST files. This tool also supports email recovery from password protected OST files. You can also save recovered Outlook data in different file formats such as .PST, .EML, .DBX and .MSG.

OST to PST conversion software displays all recovered mailbox folders in a preview list before saving at specific system folder. It supports different versions of MS Outlook, Outlook Express and MS Exchange Server.

Article Summary

You cannot access your Outlook profile or mailbox on Exchange Server in the event of OST file corruption. You can manually create a new Outlook profile for Exchange Server from local Windows Server. Alternatively you can also use scanpst.exe tool of MS Outlook to recover mailbox data from corrupt OST file. For severe corruption issues such as crash of Exchange Server, you must use a smart data recovery tool such as OST to PST conversion tool. This tool saves recovered emails and email folders in .PST file format.

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  • Marshal Hubs

    Thanks for sharing information post to recover mailboxes from corrupt ost file, I am also want to share same solution which helps to repair the corrupt ost file & convert into PST file format i.e. stellar phoenix ost to pst converter tool, Try demo version from here:

  • Hello,

    You can try to use Kernel for OST to PST is there to solve your problem. It will convert your unusable OST file to PST format, which can be further easily accessed with MS Outlook.It is the advance tool that not only repairs the corrupted or damaged OST files but also converts them to usable PST. You can take demo of this tool from here

  • Deiner

    Thank you for the article! The only shortcoming of OST to PST conversion programs is their price. They normally cost $100 and more, which is unacceptable for 1-time use. Luckily there is an affordable Coolutils OST to PST Converter for less than $40 per license

  • Tanaywan Sharesha

    Same here!

  • Royce

    Thank you very much for this helpful article. After reading it I did bit of browsing and found CoolUtils OST to PST Converter (, which i’ve been using since that time to convert corruption-prone OST files to PST.

  • By default OST files are unable to read with Outlook mailbox, in such
    situation using third party application Mailbox Recovery to restore emails from OST file on offline Exchange Server.

  • David Harper

    Thanks, it’s really very good article to restore your Outlook mailbox on Exchange Server. I got an efficient tool from that helps to solve OST file corruption and restore outlook mailbox from exchange server. This tool converts recovered Outlook data in different file formats like .PST, .EML, .DBX and .MSG.

  • Ziyoko Nonte

    OST to PST converter is an advanced tool to converts OST file into PST file and allows user to access his emails. It successfully recovers emails from inaccessible OST files and saves them in PST file for easy accessibility. The software supports MS Exchange Server 2000, 2003, 2007, 2010 and 2013.

    Read more: