In exchange 2010 environment, if you don’t provide the database name to cmdlets like new-mailbox, enable-mailbox, and new-moverequest, exchange automatically chooses a database using a process called “Automatic mailbox distribution” feature.
It sounds little weird and scary, but this might be a handy feature for environment where exchange environment is large and mailbox creation process is delegated to multiple people.
Some of the highlights of this feature
- You have options to exclude a few databases from automatic selection process
- You can choose to exclude a database either permanently or temporarily
- You can allow a mailbox creation process from a group administrators to choose mailbox database from a predefined list
You can read more details about this feature at TechNet site[http://technet.microsoft.com/en-us/library/ff872148.aspx]