Question
My Outlook 2016 is sending me an error message saying "Outlook is using an old copy of your outlook data file. Exit outlook, delete file and restart". But I can't find the OST file to delete, by the way, is it safe to delete OST files? Thank you!

OST, short for Offline Storage Table, is a local copy of the mailbox data automatically saved by Microsoft Outlook. Files saved with the extension .ost, namely OST files, store all the modified Outlook information when there is no internet connection. This allows users to access already stored data even without the internet and therefore makes offline work easier. What's better, all information will get updated when the Microsoft Outlook account regain connection to the Internet. Despite its advantages, sometimes we get an error message from Outlook, this post will explain how to delete OST file safely, recreate .ost file and recover them.

1. When Should I Delete Outlook OST File?

Outlook files are stored in both .ost and .pst modes. There are some scenarios when we need to delete .ost file.

  • Due to virus intrusion or system error, the OST file shows abnormal behavior or becomes inaccessible and unreadable, in this case we need to delete the damaged OST file and recreate new one.
  • In cases when there are synchronization errors, it can be troubleshooted by deleting the local copy of Outlook OST file or resynchronizing with the exchange server.
  • Sometimes the system may freeze or doesn't respond due to the huge size of the OST file, that's when you should consider deleting .ost files.

2. How to Delete OST File from Outlook Safely?

Before deleting an ost file, remember to synchronize Outlook with the exchange server. Deleting an ost file will erase all the offline storage file and may cause data loss, so it is recommended to have a backup of the OST file by transfering it to a new computer or exporting it into PST file.
The locations of ost files differ in different versions of Outlook, and deleting ost file is pretty straight forward if you know where to search. Here are a few steps to follow:

  • Close the MS Outlook program if it is running.
  • Go to Start and type Run, or directly open the run window by pressing Windows key + R.
  • Type the command %LOCALAPPDATA%\Microsoft\Outlook\ in the run Window and click on OK.
  • Select the OST file and click on Delete, then choose Yes to confirm the pop-up question "Are you sure you want to move this file to Recycle Bin?"

3. How to Create New Outlook OST File?

To allow Outlook function properly, you need to create new OST file after deleting the old copy. The new and older Outlook versions has different methods for the creation of an ost file, here are steps to guide you on how to recreate OST file.

1 Rebuild .ost file in Outlook 2016/2013/2010/2007

  • In Outlook 2007 open the Tools menu, while in 2016/2013/2010 click on File then from the drop-down list click Info.
  • Go to Account Settings then click on Microsoft Exchange.
  • Click the More settings button from the window that pops up.
  • Hit the Advanced tab, then choose the Offline Folder File Setting (In Outlook 2013 it's Offline Data File Setting).
  • Create a path to save the OST file, click on OK to confirm the pop-up question.
  • Select OK and then finish.

2 Rebuild OST file in Outlook 2003/2000

  • Open the Outlook application, go to the Tools menu and select e-mail account
  • Click View or change existing mail account and then Next.
  • Find the Outlook process email for the account in your order box.
  • Click on Microsoft Exchange Server, then hit change.
  • Click the More Settings option.
  • Click Advance from the menu tab and hit Offline Folder File Settings.
  • Provide a new path to save the new .ost file, then confirm the question "path/filename.ost could not be found. Would you like to create it?”
  • Click Next and then Finish.

4. How to Recover an OST File if You Deleted it Accidentally?

If you have deleted .ost files accidentally, don't worry, the possibility of restoring it is high. The first step is checking the recycle bin for the deleted file. If it is there all you need to do is hit the restore button in the recycle bin and your previously deleted ost file will be restored. But if the OST file is deleted permanently, you will need third-party recovery software to perform this task. iMyFone AnyRecover is a professional data recovery tool that has rich experience in deleted file recovery and is highly praised by customers. AnyReocver is fully compatible with Windows 10/8/8.1/7/XP, and the steps to recover deleted files are incredibly easy.

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To Conclude

When Microsoft Outlook sends you a message to delete and recreate OST file, don't be too worried as there are methods to delete OST file safely, and you can recover deleted .ost file with iMyFone AnyRecover. Even if your OST file gets corrupted, there is a way to repair corrupt/damaged Outlook OST File.