Reasons Responsible for Outlook OST Corruption

With various other features, MS Outlook enables its users to work offline. The Offline Storage Table or OST file of MS Outlook lets users work with their Outlook mailbox when there is no connectivity with the Internet is available. The changes that a user has made in the OST file are synchronized on the Server as soon as connectivity is reestablished. However, at times, because of the corruption of OST file(s), it becomes difficult for a user to sync the changes on user mailbox on the Server or more precisely it becomes difficult for a user to synchronize the changes.


Various reasons are responsible for the corruption of Outlook OST file and we can divide then into two major categories – hardware reasons and software reasons. The brief descriptions of these reasons are:

  • Hardware Reasons: Since the default location of Outlook OST file is user hard drive, thus any issue with the hard drives causes corruption in Outlook OST file. Some common problems with computer hard drive and other data storage device that corrupt Outlook OST file are:
  • Bad Sectors on the Hard Drive: If your hard drive is having bad sectors and Outlook OST file is happened to be saved on that, then chances OST file corruption are high.
  • Failure of Data Storage Device: If your data storage device like hard drive of your computer or any other secondary data storage media such as external hard drive, pen drive, etc gets failed due to virus infection, file system corruption, or any such reason, then chances of OST file data loss are high.
  • Sudden Power Loss: Unexpected power loss or abrupt system shut down while you are trying to access OST data corrupts the Outlook OST file.
  • Problem with the Network Connection: Problematic network connection or issues on network connection devices like network connection cards, routers, and cables, etc is another reason responsible for OST corruption.
  • Software Reasons: Software reasons that are responsible for the corruption of Outlook OST file are:
    • Abrupt Termination of MS Outlook: It is recommended to exit Outlook properly after closing or completion of all running activities. Abrupt or improper termination of Outlook causes severe corruption in Outlook OST file.
    • Incapability of MS Outlook: Outlook has predefined the size of its data files i.e. Outlook PST and OST file. This predefined size of these files causes deficiencies in Outlook. For example Outlook 97-2002 have limited the size of PST/OST file to 2GB, hence if you are using these version of Outlook and your PST file has crossed the limit of 2GB, then OST file will get corrupt for sure.
    • Synchronization Issues: Sometimes, you may find it difficult to synchronize your Outlook OST file with the Exchange Server. These kinds of synchronization issues corrupt Outlook OST file.

Above mentioned are some common and very frequent causes which are responsible for the corruption of OST file. However, you can avoid such situations for some cases like virus infection by enabling strong anti-virus software and using UPS for preventing sudden power outage.

However, if you are suffering from the issue of corrupt OST file, then use of an efficient tool to convert OST to PST can do the needful. Professional OST to PST converter software repairs corrupt Outlook OST file and converts it into usable PST.

Amanda is Data recovery expert from Stellar Information Systems Pvt. Ltd. She is doing research on Email recovery tips and tricks for various Email Clients like Outlook, Outlook Express & Mac Outlook etc. As well as, she focuses on mailbox conversion methods for migrating OST to PST , DBX to PST & NSF to PST etc. She loves to write about the technical issues & recovery options that help the readers to solve the problems that they face in day to day life.

Comments (5)

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    Hi Zainil – definitely some things to watch out for.

    In my experience OST corruption occurs most frequently when Outlook is not shut down correctly during the Windows shutdown process. Since I started closing Outlook completely *before* I shut down Windows, I’ve have many less errors (I think sometimes the timing of the windows shutdown process kills the Outlook processes before they finish what they’re doing).

  • Avatar

    Hi Zainil,

    Great Article, In my opinion When mostly time when We shut down of the system then the outlook is not close in properly Way during the Windows shutdown process. I think sometimes the timing of the windows shutdown process kills the Outlook processes before Finishing the Process of the outlook.Well thanks for sharing with us.

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    Hi Zainil.

    Genious Post about the Outlook Corruption, Thats fact that mostly people are careless who don’t understand. but Acc. to me its effected of our system.whenever we complete the work after that when we shutdown the system than i don’t ever check all the programs, same here of outlook that is why Outlook is corrupted. than we have to phase of this problem. really its nice info. thanks bro

    • Avatar

      Hi John,

      You are Right, and I am totally agree with your points thats fact whenever we shutdown the system than we don’t check the system and even we don’t close the programr in properly way. That is why we phase the Outlook corruption. Actually we need to shutdown system in completely way… yes john i am impressed you john. Thanks.

  • Avatar

    NIce posting about the OST curuption. The author has mentioned all the points which hold true not only for the OST curuption, but also for other programs that are not closed properly before shutting down the system.

    Great to know about the topic in more deep. Thanks for sharing it Zainil
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