Serivce Pack 2 for Exchange Server 2003 introduced some new configurable settings for information store database limits. These limits used to be hard coded depending on the version of Exchange you were using. Standard Edition was capped at 16GB and Enterprise Edition was capped at 8TB (which is the largest an Exchange Jet database can be). After applying SP2, administrators can now set arbitrary limits to the sizes of their information stores. Standard Edition users are still limited to one private and one public store, but can set both of them to a maximum size of 75GB! It is not configured this way out of the box, however!
To set a custom "hard" limit, you must modify the registry. The EDB Limit Changer tool will do this for you. This is useful for both Standard and Enterprise editions. Although Enterprise edition databases can be up to 8 TB in size, you may want to set this smaller. It is better for Exchange to crash because it hits the registry's "hard" limit than the physical limitation of your hard drive!
EDB Limit Changer requires the .Net Framework 1.1. For more information, see the blog post below!
Blog Posts about EDB Limit Changer...
• Exchange 2003 SP2 Storage Limit Tool (Dec 19, 2006)