Controlling the size of the database is set via the registry. For all the registry settings that relate to making changes on a mailbox store, note that we’ll be working in the following registry key:
HKLMSystemCurrentControlSetServicesMSExchangeIS{server name}Private-{GUID}
Registry settings that relate to making changes on a public store, you’ll need to work in the following registry key:
HKLMSystemCurrentControlSetServicesMSExchangeIS{server name}Public-{GUID}
Obviously in both cases {servername} means the name of your server and {GUID} is, well, the Globally Unique Identifier (GUID) of either the mailbox or public stores.
