The WarnFileSize registry entry
The WarnFileSize registry entry determines the maximum data that both the .pst and the .ost files can have. After this maximum data is reached, neither the .pst nor the .ost files are permitted to add any more data. However, the size of the physical file may still increase because of internal processes.
In the following table, the MaxLargeFileSize registry entry and the WarnLargeFileSize registry entry refer to a UNICODE formatted (new Large format) file, and the MaxFileSize registry entry and the WarnFileSize registry entry refer to an ANSI formatted (an earlier Microsoft Outlook format) file. The UNICODE values are set in megabyte (MB) increments, while the ANSI values are set in byte increments.
| Name | Type | Valid Data Range | Default |
| MaxLargeFileSize | REG_DWORD | 0x00000001 – 0x00005000 | 0x00005000 20,480 (20 GB) |
| WarnLargeFileSize | REG_DWORD | 0x00000000 – 0x00005000 | 0x00004C00 19,456 (19 GB) |
| MaxFileSize | REG_DWORD | 0x001F4400 – 0x7C004400 | 0x7BB04400 2,075,149,312 (1.933 GB) |
| WarnFileSize | REG_DWORD | 0x00042400 – 0x7C004400 | 0x74404400 1,950,368,768 (1.816 GB) |
The policy location for the registry entries is located in the following path in Registry Editor.
Outlook 2007
The user preference location for the registry entries is located in the following path in Registry Editor:
Outlook 2003
The user preference location for the registry entries is located in the following path in Registry Editor:
