Changing Store Limits in Exchange 2003 SP2
By default, the size limit of each database on a server running Exchange 2000 and Exchange Server 2003 Standard Edition is 16 GB (this limit is also enforced in SBS 2000/2003). Exchange Server 2003 Service Pack 2 (SP2) is supposed to remove this limit and thus allow for further DB size growth.
After installing Exchange Server 2003 Service Pack 2, the default size limit for each Exchange database is 18 GB, but can easily be configured to allow for database size limits of up to 75 GB per database.
Note: Exchange 2000 Standard Edition and SBS 2000 do not have this feature and continue to have the 16 GB limit enforced.