Exchange 2003 SP2 raises the maximum database size for the standard edition from 16GB to 75GB. By default, the size is increased to 18GB when you install the service pack, however you can raise this limit by modifying the registry, as follows:
1. Start the registry editor (regedit.exe) on the Exchange server.
2. Navigate to the HKLMSYSTEMCurrentControlSetServicesMSExchangeISSAVDALDC01Private- subkey.
3. From the Edit menu, select New – DWORD value.
4. Enter a name of Database Size Limit in GB and press enter.
5. Double-click the new value and set it to a value between 1 and 75. Click OK.
6. Close the registry editor.
You can also set a warning level that writes a warning to the event log when the database size reaches a certain percent of remaining space. To do so, you navigate to the same registry subkey as the earlier instructions show, create a DWORD value named Database Size Buffer in Percentage, and set it to a value between 1 and 100 (the default value is 10).
This check of the database size occurs once a day at 5:00 A.M. You can change this time by creating a DWORD value named Database Size Check Start Time in Hours From Midnight in the same registry key as above and setting it to the number of hours past midnight at which to perform the check (e.g., a setting of 12 means the check would occur at noon). You need to dismount and mount the Store for the changes to take effect.