What is an OST file in Outlook, and what is its purpose?

An OST file in Outlook is an Offline Storage Table file. It is a local copy of the user's Exchange mailbox and is stored on the user's computer. It is used to provide offline access to the user's mailbox data, such as emails, contacts, calendars, tasks, etc. The OST file is synchronized with the Exchange server whenever the user is connected to the network, ensuring that all changes made to the mailbox are reflected in both locations.

Can OST files become corrupted or damaged, and if so, what are some common causes?

Yes, OST files can become corrupted or damaged. Common causes of corruption or damage include viruses, malware, hardware failures, software incompatibility, and sudden power outages. In addition, OST files can become corrupted if they are not properly backed up or if they are improperly modified.

How can a user determine if their OST file is damaged or corrupted?

Check the file size of the OST file. If the file size is significantly smaller than the original size, then it may be corrupted. Try to open the OST file in Microsoft Outlook. If you get an error message or the file does not open, then it may be damaged. Try to run an Inbox Repair Tool (Scanpst.exe) on the OST file. If the tool finds errors, then the file may be corrupted. Try to use a third-party data recovery software to recover the data from the OST file. If the software fails to recover the data, then it is likely that the file is damaged or corrupted.

What are some of the symptoms of a damaged or corrupted OST file in Outlook?

Outlook fails to open or crashes when trying to open the OST file. Outlook displays an error message when attempting to access the OST file. Outlook takes a long time to open the OST file. The OST file size is larger than normal. Emails, contacts, calendar entries, tasks, and other items are missing from the OST file. Outlook displays a “file in use” error when trying to access the OST file. Emails are not synchronized between the OST file and the server. Outlook is unable to synchronize changes between the OST file and the server. Data corruption errors appear when trying to access the OST file. The OST file is corrupted and cannot be opened or accessed.

Is it possible to recover a damaged or corrupted OST file, and if so, how?

Yes, it is possible to recover a damaged or corrupted OST file. There are several methods that can be used to do this, including using third-party data recovery software, using the Microsoft Inbox Repair Tool (Scanpst.exe), or using the Microsoft Exchange Server Recovery Tool (ESEUTIL). Depending on the severity of the corruption, some of these methods may be more successful than others.

OST File Data Recovery (Outlook 2010)

Author: Vladimir Artiukh
Editor: Oleg Afonin
Updated: 8.05.2024 15:51

Discover the essential guide to restoring data from an OST file with Outlook 2010 in this comprehensive tutorial. If you’ve encountered data loss or need to retrieve files from an OST file using Outlook 2010, don’t worry. We’ve got you covered with expert solutions and step-by-step instructions to recover your data effortlessly. We walk you through the process of restoring data from an OST file with Outlook 2010 and ensuring the safety of your valuable files.

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When using a cached mode (Cached Exchange Mode), Outlook stores a local copy of your mailbox in a file with .OST extension, and this is actually the offline folders file (Offline Storage file). This file can be found in the directory C:\Users\USERNAME\AppData\Local\Microsoft\Outlook.

Because of a server failure or inaccessibility of Exchange server there is sometimes a need to fish some data from an OST file. It is for such cases that we created the present guide, by following which you can restore mail from the locally stored OST file.

In the Control Panel, open Mail element. Click on E-mail Accounts. Choose your Exchange account and click Change. In the settings panel, click on More Settings.

Now go to Advanced tab and check off the option of using the cached mode (Use Cached Exchange Mode). Save the settings by clicking Apply, then click on Outlook Data File Settings.

In the window that appears, click on Disable Offline Use. If you see a window with a warning that Outlook will not be able to work with your OST file, click Yes, which returns you to More Settings window.

Click on Outlook Data File Settings again and you will see that the button Browse is now available. Click on it and specify your old OST file (the mail from which you need to restore) and click OK twice.

After that, go back to the window of mail account settings; activate the option Use Cached Exchange Mode and then click on Next and Finish.

Launch Outlook. There must be a message that Outlook is using an old OST copy. Click OK and wait until Outlook is loading. At this stage, do not restart Outlook again by no means, as during the next launch creation of a new OST file is forced. After Outlook boots, you are supposed to see the contents of your old mailbox, including email messages, contacts and calendar information.

After that, you should create a personal folders file (.pst), connect it to the Outlook environment and transfer all necessary information there. After the transfer is completed do not forget to switch to a normal OST file in the current configuration.

Note, that this article is more relevant for Microsoft Office 2010. In newer versions of Office 2013 and Office 2016, this method of recovery of .ost file is not provided. For example, in menu «More settings» you will not find the tab «Advanced».

In this case, if you need to restore the mailbox, we recommend converting OST file to PST file and uploading the file in your Outlook 2016.