Knowledge Base

How to increase the size limit for PST file

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.


Outlook Add-in (client module) of CodeTwo Public Folders keeps a local copy of the Syncing Master (server) data in a PST file. The PST files supported on computers equipped with Outlook 2003 and 2007 can be up to 20GB in size. Outlook 2010 increases the limit to 50GB and allows to increase it further by making registry changes. Outlook versions prior to 2003 can have PST files with the maximum size of 2 GB.


To have the ability to work with larger PST files do the following:

  1. Back up data from the Syncing Master (server module).
  2. Upgrade all Outlook Add-ins (client modules) and the Syncing Master (server module) to the latest version you are licensed to use. Make sure that C2PublicFolders service is running on the Syncing Master machine.
  3. Perform the following operations on the machine hosting the Outlook Add-in (client module) for which the PST file size will be enlarged:
    1. Remove C2PublicFolders tree from Outlook profile.
    2. Exit Outlook.
    3. Remove local data kept by the Outlook Add-in (client module). To do this, go to

      C:\Documents and Settings\<user>\Application Data\CodeTwo\C2PublicFoldersClient

      (where <user> is the windows logon of the currently logged in user) and remove all files except C2PublicFolders.ini. If the default path to PST file was changed, you need to remove the PST file also from its current location.

    4. Restart Outlook and add C2PublicFolders tree to the Outlook profile manually.

Once this is complete, the Outlook Add-in will start downloading all data from the Syncing Master. This process can take some time if there is ample data on the Syncing Master available for this Outlook Add-in. This operation is also recourse-intensive for the Syncing Master, and therefore you should perform a maximum of one full Outlook Add-in synchronization at the same time.
Outlook Add-in local data is kept separately for each user and the procedure in 3. must be conducted independently for each computer, whose PST file approximates 2 GB.

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