Knowledge Base

Compacting of the local data file of CodeTwo Public Folders to reduce its size

This article is meant for users of CodeTwo Public Folders. This software has been discontinued. You can check the list of currently available CodeTwo products here.


Your PST file grew too big and you need to reduce its size.


CodeTwo Public Folders keeps a copy of data located in C2PublicFolders tree in a local PST file. The local PST file enables working in offline mode and retrieving from the Syncing Master (server) only the files that have changed.

In versions of Microsoft Outlook prior to 2003, PST file could not exceed 2 GB. When the size of the PST file approximates 2GB, you need to compact it in order to reduce its size. In Microsoft Outlook 2003 and 2007 the size of the PST file can be up to 20GB and for Microsoft Outlook 2010 and 2013 the limit was increased up to 50GB. However, compacting PST file can still be reasonable for the performance of Outlook may drop with the increasing size of the PST file.

The size of the PST file equals the total size of its elements combined. However, PST file will not shrink while the elements are being deleted. It is only when it is compacted that the data in PST file is reallocated, the size of the file shrinks and space is reclaimed.

If you want to keep the size of the local PST file at a low level, remove the right to see or read elements for the users who do not need access to these folders. The local PST file stores elements that are visible to the given user.

10 steps to compact your PST file

  1. Check where the local PST file is located. In Outlook menu, choose Public Folders, Options, and go to Other tab. The path to the local PST file is given in Local Data File field.
  2. Exit Outlook and create a back-up copy of the PST file.
  3. Create a new Outlook profile, which will only be used to compact the PST file. To do this, choose Mail in Control Panel, and click Show Profiles. Select the Prompt for the profile to be used option and click Add to create a new profile.
  4. Open Outlook with the newly created profile.
  5. If “Do you want to add CodeTwo Public Folders to the profile” pops up, click No, and don’t ask me again.
  6. Add C2PublicFolders.pst file to the profile manually by choosing File, Open, OutlookDataFile and point to the location of the PST file (see 1).
  7. In Outlook menu, choose View, FolderList.
  8. Right-click C2PublicFolders tree and choose Properties from the menu.
  9. Click Advanced button and then Compact to compact the file.
  10. When the compacting is done, exit Outlook and restart it using the standard profile. The profile that was created for the purpose of compacting can be removed or kept for later use.


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