Article ID: 179868 - View products that this article applies to.
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NOTE: These procedures only apply if you have installed Outlook with the Corporate Workgroup/Other option. This option allows you to use Messaging Application Programming Interface (MAPI) services. To determine your installation type, on the Help Menu click About Microsoft Outlook. In About Microsoft Outlook you should see "Corporate" if you have the Corporate Workgroup installation.
This article describes how to compact the Personal Folders file (PST) or Offline Store file (OST) in Microsoft Outlook, to eliminate deleted item space and recover room on your hard disk.
To conserve space on your computer's hard disk, you can delete unwanted items from the various PST and/or OST folders and then compact the files to make them smaller.
NOTE: Deleting the unwanted items from each folder only moves them to the Deleted Items folder, which is in the same file. You must delete the items from the Deleted Items folder to permanently delete them, so that Outlook can compact the file.
The compacting process does not remove all the free space from the file. It leaves either 16 kilobytes (KB) or 4 percent of the file size (before compacting) whichever is greater.
To be compacted, a file must meet the following requirements:
Automatic Background CompactionPST files that are not on your computer may require manual compaction, due to interactions between the computer where the PST files are stored and your computer.
Automatic compaction takes place as an idle task in the background. The following conditions must be true for this background task to take place:
To Manually Start PST Compaction
To Manually Start OST Compaction
(https://support.microsoft.com/kb/179870/EN-US/ )OL98: (IMO) Compacting Outlook PST Files