How Do I Open OST Files in MS Outlook?


Open OST Files in MS Outlook: OST files are created when Outlook is used with Exchange server in Cached Mode On. While these files enable users to continue working on their mailboxes even if Exchange is unavailable, if the Exchange account associated with them gets deleted somehow, these files can become orphaned and cannot be opened directly in Outlook. In such a case, accessing the data stored in them can become very difficult.

Thus, in this post, we’re highlighting a few ways to Open OST Files in MS Outlook, by using which the users can open OST file directly in Outlook. Offline Storage Table files or OST files are the storehouses for user mailbox data stored in offline mode for Microsoft Exchange emails accounts. These files are replicas of Exchange mailboxes on the local system and enable users to work on their mailboxes even when Exchange is experiencing downtime.

When the server comes back online, the changes made to the mailboxes using OST files are synced with the server to keep everything updated. Since they are tightly bound to Exchange email accounts, the data stored within OST files cannot be accessed directly without the involvement of Exchange. So if the Exchange account associated with an OST file gets deleted, the mailbox data stored in OST files may become permanently inaccessible.

OST files are also used for IMAP accounts in Outlook 2013 & 2016. It is simply a cache for outlook, if you delete it, Outlook will create a new one based on your account.

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So is There No Way to Open OST Files in MS Outlook?

The blunt answer to that question is, “No”. You cannot open an OST file directly within MS Outlook without the involvement of Exchange. OST files are usually tightly coupled with the Outlook profiles of the end users and are configured to be attached to them.

In case the Exchange account associated with an OST file gets deleted, or users need to backup or archive the respective OST files and move them to another machine, the OST files are regarded as orphaned. In such a scenario, MS Outlook might refuse to recognize the given file structure. Then, to access the data stored within OST files, the users might need to apply one of two possible solutions:

  1. Re-create OST file
  2. Use a software tool for opening the OST files in Outlook

Now that we have covered the basic premise of this discussion, let us try out these methods to open OST file directly.

Method #1 Re-create OST File if the Same Account is Available

The first way is by making use of the manual method. The manual process of opening the OST files in MS Outlook is simple and free of cost. All that the users need the same email account & can create a new copy at any time. You need to follow the below-mentioned steps:

  1. In the Control Panel of your computer system, double-click on the option Mail.

    click on mail
    click on mail

2. On the given email tab, you are required to select the particular MS Exchange account. Then, click on the option Change.

show profiles
show profiles

3. You can go ahead with clearing the checkbox labelled “Cached Exchange Mode.”

4. Click on the option “More Settings.”

5. In the given “Advanced” tab, select the Offline Folder File

6. Select the option “Disable Offline Use.” In the dialogue box that would appear on the screen, select the option Yes.

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7. You can click on the Offline Folder File setting option again.

8. Select the option OK.

9. In the Cached Exchange Mode settings, you are required to select the checkbox labelled “User Cached Exchange Mode.”

10. Select the option OK. Proceed, and click on the option “Finish.”

11. In the respective Account Settings along with the dialogue boxes of Mail Setup, select the option “Close.”

If the associated account is not available or your OST file gets corrupt. Then you can consider using a software tool for opening the OST file. We recommend using Stellar Converter for OST for the purpose.

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Method #2 Open OST File By Using Stellar Converter for OST

You can Open OST Files in MS Outlook by using Stellar Converter for OST if the associated account is not available or OST file gets corrupt. One of the most-advanced software currently available to convert inaccessible OST files into Outlook PST files is Stellar Converter for OST. This product swiftly scans OST files and easily converts all mailbox components like email attachments, contacts, calendars, etc. to PST format.

Using this trusty tool, users can extract their data stored within encrypted OST files as well. It also works with IMAP OST files and even offers the users a free preview of mailbox items before conversion. Having received numerous positive reviews from generic users and experts alike, this tool has proven to be the best option to open OST file in Outlook directly.

Steps to open OST file:

1. Select OST file by using the ‘Browse’ button then click on ‘convert’.

click on browse
click on browse

2. Now Progress bar shows the status of Outlook OST file scanning process.

3. Preview of OST file.

4. Click on ‘Save Converted File’ option & Select the ‘PST’. Click ‘OK’ to start the conversion process.

5. The Converted PST file has been saved at the selected location. Later you can import PST to any Outlook profile & access all emails.

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OST files are extremely useful and they give users access to their Exchange mailbox data on the local system. However, their dependence on Exchange account makes it impossible for users to access the data stored within them directly.

Thus, to open OST files within Outlook directly, you either need to use a manual method or convert the OST files to PST format. The manual method though free of cost is quite complicated and often fruitless. Therefore, using Stellar Converter for OST to convert the OST files to PST format is the best option.


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