Home ยป About Us

What is OST File Extension?

OST File Extension:

OST file extension is created by Microsoft Exchange Server for Offline Outlook folders when the connetion to your Exchange Server is not possible. It allow users to work offline. Using these Offline Outlook folders with the file extension .ost, user can access all the Outlook data items like Emails, Calendars, Contacts, etc. To work in a offline mode users need to enable the option: Cached Exchange mode. While working in offline mode, whatever changes has been made in the Outlook data. That changes can be sychronised to Exchange Server once the connetion to the Exchange Server is regained.

OST file make it possible to select a folder from server location, modify the content of the folder when not connected to the network and then update the folder or its corresponding server folder to make the content of both folders identical. This is basically called as synchronizing folders. The information that is synchronized includes the following :

  • Header: contain email items only i.e subject, date, time, size, message was received etc.
  • Full items: It includes all the items in a folder i.e body, attachments, objects, pictures etc.

Note: When you use Exchange Server account it is recommended to use Cache Exchange Mode.

Full Form of OST File:

OST file refers to Offline Storage Table Files(.ost) . OST file are the replicas of the folders that are present in your mailbox on the computer that is running Microsoft Exchange.

Location of OST File:

  • MS-Outlook 2000 and 2003

    c:\documents and settings\%username%\local-settings\application-data\Microsoft\Outlook\

  • MS-Outlook 2007

    c:\users\%username%\appdata\local\Microsoft\Outlook\

  • MS-Outlook 2010

    c:\documents and settings\%username%\my-documents\Outlook-files

  • MS-Outlook 2013/2016

    c:\users\%username%\documents\Outlook-files

Account Type of OST File:

The Microsoft Exchange Server, Outlook.com are the account types of OST file. When these account are being used all the items of an email message delivered and saved on the server.

Supported Application:

  • Outlook 2002, 2003, 2007, 2010, 2013, 2016
  • Exchange Server 2003, 2007, 2010, 2013, 2016

Category of Application:

Database file

Organization of Application:

Microsoft corporation

MIME Type:

Application /vnd.ms-Outlook

OST File Signature:

Hex 21 42 44 4E

Common Issues in OST File:

1. Corruption Issue

OST files are easily prone to corruption and the corrupted OST files generate a number of errors in Outlook that are listed below:

  • Large data conflict can be seen among Outlook Data items
  • Loss of Outlook data items from the mailbox
  • Cannot access a particular mailbox of user

2. Failure of Synchronization

The modification made by the user in OST file can be reflected only when it get synchronized with Exchange Server. But sometimes synchronization is missed which leads to following errors.

  • Mismatch of messages between Outlook And Outlook web application
  • Some Outlook data items such as emails, contacts, tasks get hidden automatically

3. Oversized OST

The previous Outlook versions such as Outlook 2002 generally face oversized OST file issue. Because these files are restricted to store maximum 2GB data. So when data grows beyond this limit OST file become oversized and cause following error.

  • Inability to view OST file
  • Error in adding new data to OST file

Other Miscellaneous Errors in OST File:

  1. Could not able to establish a good network connection.
  2. Corruption of hard disk lead to bad sector.
  3. Default email folder could not be open.
  4. Hidden virus along with attachments.
  5. Malicious attack on the system.
  6. Networking issues giving birth to orphaned OST files.

Extract Data From OST File:

In order to Extract data from OST file you can use OST Extractor which has various inbuilt facilities to extract data without Exchange server setup. You can launch the tool and using its step by step guidance.

Conclusion:

The aimed of this article is to discuss the OST file extension. All the technical specification of an OST file are listed above. Various kinds of errors that can occur in an OST file related things with an automated tool has been discussed also. As it provide recovery against highly corrupted files without any data modification.