Right now, about two thirds of organizations use mailbox quotas. What ends up happening is employees create personal folders, PSTs in Exchange or NSF files or Lotus, and they either manually move messages into those personal folders, or they just delete them so they don't hit the quota.
can do is create a separate mailbox, an archive mailbox, where based on policies, whether it's messages older than a certain date or messages of a certain size, are automatically moved from the primary environment into a secondary environment. Therefore, those messages do not count against a quota, and those messages are also still available for use. Organizations can continue to use mailbox quotas with archiving, but the archiving will actually allow for an infinite mailbox. That infinite mailbox is hopefully stored on much cheaper disk and an even cheaper server, if possible. You can still have mailbox quotas with archiving, you can just make sure the messages are centrally and readily available.
Go back to the beginning of the Email Archiving in 2008 FAQ Guide.
Dig deeper on Data storage compliance and archiving