How to Fix Outlook OST File Size Not Reducing After Archiving Error?

  •   Written By
  • Published on
    April 3rd, 2020
  • Updated on
    December 13, 2022
  • Read Time
    4 minutes
Rate this post
Summary:- “The increasing size of Microsoft Outlook is obvious because of its extensive use in various organizations for emailing purposes. Even when a user erased or deleted these email items the size of OST files does not reduce so much. Even the archiving method does not help. This leads to error i.e. Outlook OST size not reducing after archiving. Now the question is is there any trick to rectify this error? Can we handle this error manually? The answer is “Yes”. There are some strategies to solve these issues. In this blog, we will share the manual as well as an automated method to fix Outlook OST file size not reducing after archiving error.” 

Manual Method to resolve “OST file size not reducing after archiving

Method1: Manage the size of Outlook’s mailbox

For this, users can take the help of Mailbox-cleanup tool to view the size of the entire Mailbox of Microsoft Outlook. With this, the user can see the size of the particular folder. Users can archive the older emails to an archive Outlook data file & after this, they can empty the folders of deleted-items. Follow the steps to manage the size of the mailbox of Outlook data file.

  • Firstly, Click on the File tab
  • Now, click on Tools & then click on Mailbox Cleanup
  • After this, Follow any of these mentioned steps:
  • For viewing the size of the entire mailbox and of an individual folder, click on view-mailbox-size

If you wish to find the older email items, do this:

  • Choose to find items older than x, which is the required values days
  • Then, Put in a number between 1 & 999
  • Finally, Click on find
  • Choose to find items bigger than X KB
  • Then after, type in a number between 1 & 9999
  • Now, click on Find

For moving older items in the mailbox to an archive Outlook-Data-File, Then click on AutoArchive

Note: How to Convert OST to PST in Outlook?

Method2: Compact the size of OST data file

Offline storage table file belongs to Microsoft exchange server account. In addition, these files are bot deleted whereas the exchange server runs in the process of deletion. So only shrinking of files will be another option to enhance the performance of Outlook. 

Follow these steps to compact OST files you can follow these steps one after the other.

  1. Delete or erase the email which is not needed any longer
  2. After this, open the Folder-List view
  3. At the bottom side of the Navigation Pane, Click on folder list icon. You may also press CTRL+6 for this.
  4. Now, right-click on the folder of deleted items once again the Navigation Pane
  5. Then after, click on Empty folder. >>File>>Account settings
  6. Once it is done, click on Data files tab, click on the file that needs to be compacted.
  7. Next, click on settings>>Advanced tab>>Outlook-Date-File settings
  8. Click on OK
  9. There is no requirement of present Outlook on the compacting process of offline OST file is done
  10. If you want to delete any item, from offline and online folder do this:
  11. Next click on settings>>Advanced tab>>Outlook-Data-File Settings
  12. Choose the item that needs to be erased
  13. Then after press Delete

This is the manual method through which you can fix Outlook OST file size not reducing after archiving error. But for performing these methods you need a technical background. This method is too lengthy as well as tough. There may be a chance of losing data during the execution.

Alternative Method

In order to fix Outlook OST file size not reducing after archiving Error, you need OST to PST tool. This tool has a user-friendly GUI. This is easy to use, even a guy with a non-technical background can also install & run the software. The process of execution with this tool is very easy. It keeps the data secure & private after the successful execution.


In this blog, we have shared manually as well as an alternate method to fix the outlook OST file size not reducing after archiving error. The manual method will take time & this is too lengthy. You need a technical background. But automated methods will do work quickly & securely. You don’t need more technical background for performing this method. 

Related Post