Rules can only be set on folders in Microsoft Exchange Server-based information stores. They are accessible in the following folders subject to the restrictions defined in Rule Actions:
Private information store(mailboxes) Supports rules on all folders in both the IPM and non-IPM subtrees. The user interface of the Microsoft Exchange Client exposes rules only for the Inbox, but the server supports rules for all folders in mailbox information stores.
Public information store Supports rules on all folders in both the IPM and non-IPM subtrees. Only the folders in the IPM subtree have a user interface in the client. Folders in the Favorites folder in the public information store also support rules.