Fixed: “Outlook OST File Too Large” Issue By Compacting [2024]

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Written By Andrew Jackson
Anuraag Singh
Approved By Anuraag Singh
Published On March 11th, 2024
Reading Time 5 Minutes Reading

OST stands for Offline Storage Table. OST file is a replica of the user’s mailbox on the Exchange Server that is saved locally on your desktop. It helps you to work offline in the absence of an Exchange Server and holds the entire Outlook information since the last synchronization. There are many situations when the OST file is larger than the mailbox and the user wants to compact the offline OST file. In this blog, we are going to discuss how to deal with the “Outlook OST file too large” issue.

Quick Fix: You can use the SysTools OST Splitter tool that helps you to split oversized OST files. This software is helpful to deal with all Outlook versions.

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Why Do We Need To Compact OST File?

Your MS Outlook mailbox grows as you receive and create items and it makes your OST file too big. The size of your OST file may not decrease even when you delete some items. It can make your system slow if your system does not have a high-performance HDD. Instead of investing in a new disk, it’s better to compact the Outlook OST files to get rid of OST files too large problem.

When you delete an Outlook Item from your Outlook profile, the item goes to the Outlook deleted folder. Since the item can be recovered from there, it means the item still takes up some space in the OST file. Now, when you empty the deleted item folder, the item is deleted from the OST file too. However, because of the way OST files work, the space occupied by the item is still unavailable for other uses. It makes your OST file bigger and bigger over time, even if you delete some items or keep the same number of items in Outlook.

Compacting OST files reclaims the space that was previously occupied by an item. So, compacting can reduce the space that the previously stored items occupy in the OST files on your HDD. Alternatively, you can convert the OST file to PST to prevent future corruption issues.

How to Fix Outlook OST File Too Large Issue?

In this segment, we will discuss the manual approaches you can opt for to fix the OST file size bieng too large issue. We will share the step-by-step methods for Outlook versions 2007, 2010, and 2013. So, whare are we waiting for? Let’s get started.

For Outlook 2007

Follow the instructions below to reduce or compact OST file size in Outlook 2007.

  • First, Delete items that you do not want to keep in your OST file.
  • Empty your deleted item folder
  • Click the File tab and select the Info tab
  • Click the Account Settings tab, and then click on Account Settings again
  • Select MS Exchange Server Account ID and then click on Change
  • Click on More Settings
  • Click on the Advanced tab, and then click on Offline Folder File Settings
  • Click on Compact Now and then OK.

For Outlook 2010

You can follow below-mentioned steps when the Outlook 2010 OST file has reached maximum size.

  • Delete items that you do not want to keep in your OST file.
  • Empty your deleted item folder
  • Click the File menu and select the Info tab
  • Click the Account Settings tab, and then again click on Account Settings
  • Select MS Exchange Server Account ID and then click on Change
  • Click on the More Settings option
  • Click on the Advance tab, and then click on Offline Folder File Settings
  • Click on the Compact Now option and then OK.

This will compact offline OST files and resolve the OST file too-large error in Outlook 2010.

For Outlook 2013

You can follow these steps to compact the OST file without any limitations.

  • You have first to Delete items that you do not want to keep in your OST file.
  • Empty your deleted item folder
  • Click on File and select the Info tab
  • Click on Account Settings tab and then click on Account Settings again
  • Select MS Exchange Server Account ID and then click on Change
  • Click on More Settings
  • On the Advanced tab, click on the Outlook Data File Settings option
  • Click on Compact Now and then OK.

Note: Ensure that your OST file is equal to or greater than 16 KB. You may not be able to compact Outlook OST files manually if the size is less than 16 KB. In addition, this option cannot compact your corrupted OST file.

Tip: Follow the steps and open the OST file in another Outlook profile.

What If Your OST File Gets Corrupt Due To Large Size?

If an OST file is too large, it can lead to conditions of severe corruption and data loss. The compact OST file option will not work in this case because you cannot compact a corrupted OST file. In this situation, you can use a professionally-suggested automated tool to recover your data. OST Recovery tool is recommended by many users as one of the best tools, due to its potential to repair damaged OST files (both minor corruption and major corruption). In addition, the tool allows you to export your corrupted OST file into healthy & required email file format.

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By Andrew Jackson

I am SQL DBA and SQL Server blogger too. I like to share about SQL Server and the problems related to it as well as their solution and also I do handle database related user queries, server or database maintenance, database management, etc. I love to share my knowledge with SQL Geeks.