So you administer Microsoft Exchange Server 2010. You must then know that mailboxes are stored in mailbox databases, and, based on previous versions, you also know that you need to specify a mailbox database when creating a mailbox.
Now, one day, you go to create a mailbox on Exchange 2010 and forget to specify a mailbox database. And you don't get an error. You would then ask "Where'd it go?". You eventually discover that the mailbox was created on some random mailbox database that you didn't specify yourself. Don't worry! Exchange administrator, meet the new "automatic mailbox distribution" — feature that omit the steps of providing a mailbox database, and instead Exchange picks a mailbox database for you. Now, you might see this as a really cool feature, or you might think it's pretty scary."
Take a look at the article linked below and let us know what you think of this new feature.
More Info: Where Did That New Exchange 2010 Mailbox Go?