Reducing outlook mailbox OST file size

Owned by Former user (Deleted)
Last updated: 20-Apr-23 by Former user (Deleted)
3 min read

Please follow the below guide if you think you need (or have been told to) clear down the size of your mailbox.

Method 1: Disable shared folder synchronization

Shared Folders can also quickly increase the OST file size and cause Outlook performance issues. To resolve this, disable Shared Folders synchronization by following these steps:

  • Click File > Account Settings > Account Settings.

Find location of OST of file

  • Under the Data Files tab, select the OST file.

  • Click Settings > Advanced > Outlook Data File Settings…

  • Uncheck the Download Shared Folders option and click OK.

Outlook data file settings...

  • Restart Outlook and wait for synchronization to finish.

 

After you make this change, none of the shared folders in the secondary mailbox will be available to you in Outlook when you are working offline. However, all folders in the primary mailbox will still be available to you when you are working offline.

Method 2: Delete large Outlook emails and attachments

Deleting large emails, undoubtedly, is the wisest technique. Rather than randomly deleting large-sized files, you can follow a systematic approach to manage Outlook attachments . The steps are:

  1. Open Outlook. In the folder list, click Search folder, then select New Search folder.

  2. Scroll down the list and under Organizing Mail, select Large mail. Click Choose under Customize Search Folder.

  3. Specify a size in the ‘Show mail greater than’ box (for example 6000 KB). Click OK to continue.

  4. Click OK again and a folder named ‘Larger Than 6000 KB’ is created under Search Folders. This newly created folder will get updated with the mails of size more than 6000 KB automatically.

 

Method 3: Compress the outlook PST data file

In Outlook, Outlook data files can be compressed manually. Compressing files would help in restoring some space in the mailbox. Before starting the procedure, delete the items that are not required. In Navigation pane, right-click the Deleted Items folder and then click Empty ‘Deleted items’ folder. Then follow the steps given:

  1. Launch Outlook. In the File tab, select Account Settings and then click Account Settings.

  2. Click the Data Files tab, select the PST file to compact, and then click Settings.

  3. In Outlook Data File dialogue box, click Compact Now. This is the final step.

 

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