Going to the New Larger Outlook 2003 PST File Size Limits

Supposedly Outlook 2003 offered new, larger file size limits for outlook.pst files above the 1.8gb/2.0gb limits that previous version had. If this is true, how come users that install or migrate to 2003 are still hitting the limit and getting a maximum file size error? The answer has to do with default values and how things get setup during the upgrade/installation.

First, here are the related Microsoft KB articles:

• 830336 - The .pst file has a different format and folder size limit in Outlook 2003
• 832925 - How to configure the size limit for both (.pst) and (.ost) files in Outlook 2003
• 842784 - You cannot deploy Unicode .pst files when you use the Custom Installation Wizard from the Office 2003 Resource Kit

These articles were helpful in finding out about the new limits and why I didn't get to use them (the PST in question was set up as the Outlook97-2002 portable/backward compatible format instead of the new large format). However, I couldn't find an article about how to actually migrate to the new format.

In general, to migrate to the new larger file, you need to create a new large format file, start outlook using that file, then migrate (import) your old pst into your new pst.

Warning: once you convert to the large format, you will not be able to read your new PST with previous versions of Outlook. You can still export to another old-format PST file, then read that file, but you can't read the new format directly.

These instructions are general guidelines that follow the steps I needed to do. You may see different windows and different values depending on your setup. Be sure to make a backup and take the usual precautions. With that said, here's how I was able to migrate to the new large PST file format:

• Start Outlook 2003
• Create a large format PST: Click File/New/Outlook Data File.
• Select "Office Outlook Personal Folders File (.pst)", NOT "Outlook 97-2002 Personal Folders File (.pst)" and click OK.
• Enter the name: large.pst
• Note where the file is being created. This is usually the same place as your original PST and is usually:\Documents and Settings\usersname\Local Settings\Application Data\Microsoft\Outlook\
• Click OK, then click OK again.
• Exit Outlook.
• Open Explorer or a cmd.exe window and navigate where you saved the large.pst.
• Rename outlook.pst smalloutlook.pst
• Rename large.pst outlook.pst
• Exit Explorer or cmd.exe
• Start Outlook. You will get a crash error and a message offering to start in Outlook Safe Mode. Do that.
• Exit Outlook.
• Start Outlook.
• Import your old file: Click File/Import and Export, then select "Import from another program or file", then click Next.
• Select Personal Folder File (.pst), then click Next.
• Select the smalloutlook.pst file you renamed your PST to in the previous steps. Select "Do not import duplicates" and click Next.
• Select "Personal Folders", "Include subfolders", "Import items into same folder in:", and select "Personal Folders". Click Finish.
• Since you are probably following these instructions because you have a large PST, the import will take awhile. Wait for it to finish and you should be all set.

The file you are now using will be able to go up to 19gb. If you need more than that, look into KB article 832925. If you will be deploying using an Administrative share, look into the KB article 842784 so that you can start with a large format file and avoid having to convert.