I have been working through a bunch of Microsoft Exchange migrations recently. One of the issues that we have seen has to do with the size of the exported PST file. By default, the maximum size of PST files has been limited to 20GB for Outlook 2003 and 2007, and 50GB for Outlook 2010 and 2013.
This limit can be increased or decreased via two registry settings.
- WarnLargeFileSize – This value sets warning threshold in MB for the maximum size of a PST file. The maximum is 4090445042 (That is about 4PB!)
- MaxLargeFileSize – This value determines the maximum size in MB that can be written to a PST file. This should be set to about 5% higher than the warning size above. This maximum is 4294967295.
Here are some common values that could be used:
- 30GB maximum (29GB warning) = 30720 (29696)
- 75GB (73GB) = 76800 (74752)
- 100GB (95GB) = 102400 (97280)
- 150GB (145GB) = 153600 (148480)
- 200GB (190GB) = 204800 (194560)
- 500GB (480GB) = 512000 (460800)
- Are you sure you want such a large PST file after this?
The registry settings are found or created here, depending on the Outlook version.
- Outlook 2003 HKCU\Software\Microsoft\Office\11.0\Outlook\PST
- Outlook 2007 HKCU\Software\Microsoft\Office\12.0\Outlook\PST
- Outlook 2010 HKCU\Software\Microsoft\Office\14.0\Outlook\PST
- Outlook 2013 HKCU\Software\Microsoft\Office\15.0\Outlook\PST