Applies to:
ONLY Exchange Server 2003 with SP 2.
Problem:
With MS Exchange Server 2003, and NO service pack, the maximum database size is 18 GB. With the release of Service Pack 2 for Exch 2003, this value is now DEFAULT 18 GB, but can be increased up to 75 GB for Standard versions.
Solution:
Modify the registry settings:
1) Open REGEDIT.
2) Navigate to the following key:
“HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\
\Private-013e2e46-2cd7-4a8e-bfec-0e4652b94b00″
3) Create a new DWORD, with the name (remember caps! – no quotes):
“Database Size Limit in GB”
4) Give your new DWORD the value of the desired size, in GB. So for a 25 GB database, simply enter 25.
5) Restart the Microsoft Information Store from Services.
Thats it. 
