Microsoft Exchange 2003 is quite an old product now – but still widely used in production. What I’ve found over the last few months doing migrations is that many people are either running Service Pack 1 or haven’t changed the registry key that allows you to increase the store size.
You may get an error like this in the event log, event id 1216
When you install the service packs, they do not increase the store size. This must be done manually. As you can see, Exchange is SP2 which has a 75GB limit. This is also the case when upgrading Exchange 2003 Standard to 2003 Enterprise.
To fix this, you must edit the registry. Edit the following key:
Under this key, you will find the private and public stores.
Change ‘Database Size Limit in Gb’ to 75.
You will now need to dismount the database and remount it.