Things you should know about OST file

Last Modified: September 10, 2019

Microsoft Outlook is a personal information manager and mainly used as an email application, which includes emails, calendars, contacts, tasks, journals, etc. The first outlook version was introduced in 1997 included in Office 97 and bundled with Exchange Server 5.5.

MS Outlook uses PST (Personal Storage Table) and OST(Offline Storage Table) file format to store messages, calendar, and other items on the local computer. Mainly PST files used to store archived items and OST files maintain Offline availability.

What is the OST file?

OST or Offline Storage Table is an Offline Folder file. Most account types, such as Office 365, IMAP, Exchange, and Outlook.com accounts use the OST file to store a copy of your mailbox on your local computer. With the help of OST file, you can access emails, calendars, task, contacts, and journals that have been previously downloaded. However, you can’t send new messages until your internet connection is restored. When the internet connection is available all the changes are automatically synchronized with the Exchange server.

What is the difference between OST and PST?

  1. OST file is can be used when no internet is available. You can access all the items that have been previously downloaded whereas PST is used to store all the data on the local machine.
  2. OST file support only MS Exchange Server whereas PST can be used with Exchange but not recommended. Apart from this PST is also compatible with other servers.
  3. The OST file is appropriate for domains with limited internet connections however such is not the case for PST files.

How to find the OST files location?

For Outlook 2019, 2016, 2013

  1. Open MS Outlook
  2. Go to File option
  3. Select Account Settings and click on the Account Settings
  4. Select the Data File tab and click on the Open file location

For Outlook 2010

  1. Open MS Outlook
  2. Go to File option and select Info
  3. Select Account Settings and click on the Account Settings
  4. Select Microsoft Exchange server from the list and click on Change
  5. Click on More Settings
  6. Click on Advanced tab and click on the Offline Folder File Settings

For Outlook 2007

  1. Open MS Outlook
  2. Click on the Tool Menu and select Account Settings
  3. Select Microsoft Exchange from the list and click on the change button
  4. Select Account Settings and click on the Account Settings
  5. From Change E-mail Account screen select More Settings
  6. Click on Advanced tab and click on the Offline folder file settings

What are the reasons for the OST file corruption?

The OST file is very useful when there is no internet connection is available. But the OST file is very sensitive and similar to other files the OST files also corrupt. Most times, the OST files get corrupt because of unreliable internet connectivity. However, there are many reasons for OST file corruption. These reasons can be categorized into two parts.

  1. Hardware Related
  2. Software Related

Hardware Related

The hardware related issues can be categorized into three parts.

  1. Data Storage Failure
  2. Sudden Power Loss
  3. Network Connection Failure

Data Storage Failure: This is one of the big reasons for OST file corruption. In this case, your hard drive has some bad sectors and the OST file is stored on those sectors.

Sudden Power Loss: If power loss happens during the synchronizing process, that may corrupt your OST files.

Network Connection Failure: Because of inappropriate functionality of the routers, hubs, network interface cards, can affect the OST file synchronization process and it maximizes the chances of OST file corruption.

Software Related

Malicious Software or Virus: If your system is virus-infected, then the chances of OST file corruption may increase. The virus can affect your OST file and make them inaccessible.

What are the most common and uncommon errors in the OST file?

Here is the list of some most common and uncommon errors. Let’s discuss what you should do if you find these error messages.

  1. Errors have been detected in the OST
  2. Exchange is currently in recovery mode
  3. The file OST is in use and cannot be accessed
  4. OST file internal error code 0000000E

Note: Please keep a backup before implementing these methods.

Errors have been detected in the OST:

The following message shows OST file corruption. In this case, close all the email applications. You can try these manual methods to repair OST file.

Method 1: Restore Backup

This is the simplest way. You just need to replace the corrupted OST file with a very recent backup copy.

Note: Please Replace with the most recent backup. If you don’t have a recent backup, then you could lose data that was changed after the backup was taken.

Method 2: Remove all offline data and recreate OST

  1. Find OST file on your machine
  2. Right-click on the folder and select properties
  3. Select Clear Offline Items and click on the OK button
  4. Open Outlook
  5. Go to Send/Receive tab and click update folder

After the process Delete the OST file. When outlook sync with Exchange, a new OST file will be automatically created and all mailbox data will be downloaded into it. If the recent changes did not sync with the Exchange mailbox, then you might lose some data.

Method 3: Create a new MS Outlook profile

This error also occurs if your Outlook profile is damaged. In such a case, delete the current default profile and create a new default Outlook profile:

  1. Open MS Outlook
  2. Go to File option
  3. Select Account Settings and click on the Manage Profiles
  4. Click on Show Profile
  5. Click on Add
  6. Type a name for the profile
  7. Click on OK

Exchange is currently in recovery mode:

In this case, the user can choose Online mode or Offline mode. In online mode, users can access the MS Exchange but cannot access the OST whereas offline, you can access OST but cannot access the MS Exchange server. If you are facing this error, then you can try these methods.

Method 1: Disable Cached Exchange Mode:

  1. Open Microsoft Outlook
  2. Select the File option
  3. Click on the Account Settings and select Account Settings
  4. Click on Change
  5. Unselect the Use Cached Exchange Mode option
  6. Click on Next
  7. Delete the Offline OST
  8. Restart Outlook and cached Exchange mode will be enabled

After the process, a new file will be created automatically.

Method 2: Create a new MS Outlook profile

  1. Delete the current default Outlook profile
  2. Create a new Outlook profile
  3. Set a newly created profile as the default

The file OST is in use and cannot be accessed

This message shows that the OST file is used by another. But it's not necessary; there could be several reasons

  1. Synchronization issues between the OST and associated Exchange mailbox
  2. Applications conflicting with outlook
  3. Unreliable network connectivity

In this case, you can try to Disable Cached Exchange Mode.

OST file internal error code 0000000E

It is a very common issue, and it occurs because of synchronization interruptions. As a result, OST files become inaccessible.

In such a case, you can use Outlook inbuilt utility ScanOST.exe. But this utility only works to fix minor issues, and it’s not available in MS Outlook 2010 and later versions.

If you are facing these messages firstly try these manual methods. If these don’t work, then try OST to PST Converter tool. This tool easily recovery any corrupted OST file and convert into a healthy PST file. You can also export selected items. By using this tool, you can convert OST to PST, MSG, EML, DBX, PDF, HTML, etc.

How to convert OST to PST without using third-party OST to PST converter?
  1. Open Outlook
  2. Login MS Outlook with the Exchange account that was used at creation time
  3. Go to File option
  4. Select Open & Export option
  5. Click Import & Export option
  6. From Import & Export wizard Select Export to a file
  7. Click on the Next button
  8. From Import a file wizard select outlook data file(.pst)
  9. Select the folder which you want to export
  10. Set location for the exported file and also select do not export duplicate items.
How to recover corrupted OST file?

You can try above mentioned manual methods to convert OST to PST. If none of the methods work for you, then try the most advance Convert OST to PST tool. This tool works well on any type of corruption and even it can recover permanently deleted items. By using this tool you can repair your OST file and convert it into many file formats. This tool allows you, migrate OST to MS office 365 and also you can export OST to PST, EML, MBOX, MSG, HTML, RTF, PDF, MHTML, TXT.

Apart from this you can convert OST to PST and use split PST option to broke PST into manageable sizes and also you can generate an analysis report of the total export items. This application supports all the versions of MS outlook like 2019, 2016, 2013, 2010, 2007, etc.

You can also try the demo version of OST to PST software. You can open and view all the entire data and also you can save 25 items per folder.