OST [Offline Storage Table] file or Offline Outlook data file is automatically created when you configure Outlook with IMAP, Exchange, or Outlook.com account. It is a copy of your mailbox items, like emails, notes, journals, events, calendars, contacts, etc. on the mailbox server. There is a defined maximum size limit for OST file based on the Outlook version. For example, in Outlook 2010, 2013, and later versions, the maximum size limit for OST file is 50 GB and in Outlook 2003 and 2007, the limit is 20 GB.
When the OST file becomes large or reaches the defined limit, you may start facing performance issues or encountering error messages in Outlook. Moreover, large OST files are prone to corruption or damage. If your OST file becomes large, you need to reduce the file size to avoid such issues. In this article, we will see how to deal with large OST file and reduce its size.
Ways to Deal with Large OST File
The best way to deal with the large OST file is to reduce its size. For this, the first thing you can do is delete the unnecessary or unwanted emails and other items from the OST file. Next, you can check the emails with large attachments, save them on your system, and then delete them. However, if these steps do not help much, then follow the given methods to reduce the OST file size.
Method 1: Compress or Compact OST File
Outlook comes with the Compact feature that helps to compress the OST file by removing the empty spaces created by deleted emails and other items, thus reducing the file size. Follow the steps given below to compact the OST file:
- Open Outlook and then go to File.
- Now, select Account Settings and then click on Account Settings.
- In the Settings window, click on the Data File tab and then select the OST file that you want to compress/compact.
- Now, click on Settings. In the next window, select the Advanced tab. Click on the Outlook Data File Settings option.
- In Outlook Data File Settings dialog box, click on Compact Now and then click OK.
This will reduce the size of your OST file.
Method 2: Use Mailbox Cleanup Tools
You can also use the Clean Up Tools in Outlook to clear old or large mailbox items and reduce the OST file size. Follow the steps given below:
- Open MS Outlook and navigate to File.
- Select Info, click on the Cleanup Tools option, and then select Mailbox Cleanup.
- In the Mailbox Cleanup window, click on the View Mailbox Size to view the current size of your mailbox.
- To find and delete older items, select the radio button Find items older than and then enter the number of days. You can also choose Find items larger than and enter the size.
- You can click on Empty to empty the deleted items folder. Also, you can select Delete to delete alternate versions of items.
This will help reduce the size of your OST file.
In Outlook, Shared Folders can take a considerable amount of space. If you’re using shared folders, then you can disable the Shared Folder synchronization. Follow the steps given below:
- Go to File, select Account Settings, and then click on Account Settings.
- In the Settings window, click the Data Files tab and then select the OST file.
- Under Data Files tab, click on Settings, select Advanced, and then click Outlook Data File Settings.
- Under Cached Exchange Mode Settings, uncheck the Download shared folder option and then click OK.
Method 4: Archive Older Emails
Another way to deal with the large OST file is to archive old emails and other items using the Archive feature. This can help you to significantly reduce the size of OST file. You can follow the steps given below to archive old emails in Outlook:
- Open Outlook, go to File, and then click on Info.
- Select Tools and then click on Clean Up Old Items.
- In the Archive window, click on the radio button – Archive this folder and all subfolders and then select the folders you want to archive.
- Choose a date in Archive items older than and then click Browse button to save the items. Click OK to finish the process.
The archived items will be saved in a PST file.
Conclusion
Large OST files are prone to corruption and can create performance issues in Outlook. Therefore, you need to reduce the size of OST file to prevent such issues. The above-mentioned methods can help you to deal with large OST file and reduce its size. However, if your OST file becomes inaccessible due to large size, then you can use an OST to PST converter software, like Stellar Converter for OST. It can extract all the data from large inaccessible or orphaned OST files. This software saves the extracted data in PST and various other formats. It also comes with a feature to Auto Split, which can help you to split large OST file data into multiple smaller PST files. It also has an Advance Filter feature that allows to include and exclude specific items when saving the converted OST file.
