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Our Business accounts have a powerful archiving/journaling feature. What this allows you to do is per-user, you can enable archiving of all incoming/outgoing email. This email goes into a separate account and folder structure that only the business administrator can access. The archive account has unlimited storage, and special ACLs on folders so users can't delete emails (unless specially overridden). This means the archive is a true journal of all received/sent messages for a user, which is useful for compliance and tracking.
The plan was to always charge for this feature and it's been documented as such in the help, however the code was never actually in place to do this.
The code for this is now done, and all affected users were sent an email, informing them that archive billing would be starting soon, and it has now been enabled.