How to Temporarily Increase the Exchange 2000 16-Gigabyte Database Size Limit?
MS KB 813051 has info on this issue:
The Microsoft Exchange 2000 Server message database (MDB) automatically shuts down and does not restart when it reaches the maximum size limit that is permitted. This behavior is by design to prevent the database from trying to insert more data into the database file than it was designed to hold. Frequently, you experience this behavior when you are running Microsoft Exchange 2000 Server Standard Edition. Exchange 2000 Server Standard Edition limits the database size to 16 gigabytes (read more – What’s my Exchange 2000/2003 Version?).
A new update to Exchange 2000 has been developed that permits you to temporarily increase the database size limit by 1 gigabyte. By increasing the size limit, you can selectively remove unnecessary database content (read more – Delete Messages from Mailboxes by using EXMERGE), defragment the database (read more – Defragment Exchange 2000/2003 Server Databases), and reduce the database size to a manageable level that is below the defined limits for database size.
Follow these easy steps:
Temporary DB Size Limit Extension
If the Temporary DB Size Limit Extension registry value exists for a specific database and if the value is set a value other than zero, the database size limit (if any) is increased by 1 gigabyte. However, this registry value is not read dynamically; it is only read when a database is started. Therefore, you must either reboot the server or restart the Information Store service.
When the Exchange Information Store starts, an event 9657 will be logged as a warning to inform you that you are using a temporary database size limit.