In Exchange 2010, you can use Multi-Mailbox Search to search mailboxes for e-Discovery or similar purposes. To preserve data in user mailboxes and protect its integrity, you can place a mailbox on ...
Updated Jul 01, 2019
Version 2.0
Blog Post
@exchangeuser: Discovery uses two types of mailboxes - 1) discovery mailboxes to store search results (setup creates one discovery search mailbox, you can create additional discovery mailboxes) and 2) a system/arbitration mailbox to store search metadata, which you shouldn't need to touch. See Understanding Multi-Mailbox Search for details.
Are you referring to the default discovery search mailbox? Discovery mailboxes should not grow if you're not performing any searches.