Challenges faced when working on Outlook OST file

Let’s start by taking a look at what an .OST file is. An .OST file is an offline folder file created when you are connected to an Exchange Mailbox in Outlook.

The next step is to look at what a .PST file is. This is a personal storage table where a backup of your email messages, calendars, tasks etc. is kept or if you have rules within your outlook to move mail to a specific folder located in the .PST file.

.OST files can grow quite large over time, especially when users have 20GB to 100GB mailboxes. You can open an .OST on a computer that has the same alias as the current one.

Backup Lost: The first problem you have is that backups run once a day and if the Backups are not fulll proof, you have an issue.

  1. Backup runs and you have a power surge or drop and the backup fails at a certain % and needs to be manually resumed.
  2. Issue with backup-space when the tape gets full or if you doing disk backups then you run out of disk space and again the backup fails.

Having said this, data written after the backup will be lost and users only have there .OST files to rely on. Additionally, Exchange is now not available or a new database would have to be created and a restore done but the same results in data loss.

End users want to know that they will have all their information in Outlook as soon as they click the button.

OST file is missing: The other challenge comes in when the end user opens up their outlook and either they are presented with a Temp profile as the .OST file is missing or not accessible for some reason or has corrupted. This can be an issue because they are running a version of Outlook like an Office 365 Package and have an on-premise Exchange Server.  This can be quite cumbersome for an IT person to firstly find and recover the data. The second challenge they encounter is not being able to access the data in the .OST file.

Exchange Server Fails: Working in many environments where end users work on desktops and just lock their desktop before going and leave outlook running, it then caches a copy locally on the machine. Even when disaster strikes if the Exchange Server fails or if backups are not available or not done at all you have the option to do an .OST to .PST restore at hand – very useful information to you and good news is that you are able to give to your end users or clients.

OLD OST file delete: Other problems that we have seen is when users move machines or a user leaves the company and the mailbox is deleted by the Exchange Admin and you are left with the old laptop and now need the access to the old data.

The only problem or challenge with this is time, an .OST file of 10GB or larger will take a bit longer to convert but the data should be available.

Your Admin now want to know what my solution to get all the emails back is.

The first option is to try and repair the Exchange database, take note you might have data loss and considerable downtime with this especially when the Exchange Databases are very big. Also if your backups did work you would still have data loss after the backup was run and before the next backup starts.

There are many tools on the internet to assist you with this but one Tool that stands out and has been tested in many environments and many customer environments is the .OST to .PST tool provided by Stellar Data Recovery.

If you would like to know more about this product, download the software from here:

free download

Stellar Converter for OST works well with all versions of Microsoft Outlook. If your end users are running Office 2000 or Office 2019, don’t despair, the .OST File can be converted to a .PST file that can be attached to Outlook again.

Here is a sample of the application provided by Stellar Converter for OST:

The process is straightforward, you select the users’ .OST file, located in the user directory within windows; it is a hidden directory so you need to ensure that you show all files on the computer.

Select the .OST file and let’s start the scanning. Once it is complete you can export the file to .PST. Once done you can now import it or attach it to Outlook again.


As an IT Admin or IT Manager, you have the option to provide a solution to your users or your clients that you are able to assist them with the recovery of email in the event of a failure on Exchange or its backup on a user’s machine.

What’s our MVP take on OST to PST Converter tool from stellar.

You may also like to read:  10 tips for troubleshooting Outlook problems

Synchronization problems occur in Outlook and in Outlook Web App

  1. Sebastian Sophia August 21, 2018
  2. Linda Newnham August 21, 2018
  3. Penny Freeman February 28, 2018
    • Eric Simson March 1, 2018
  4. Clifton Ross December 14, 2017
  5. Linda Ramos December 13, 2017
  6. Asher December 11, 2017

Leave a Reply

Your email address will not be published. Required fields are marked *

Time limit is exhausted. Please reload CAPTCHA.