Certain rules require a specific client to establish a client session before the rule can take action. When a rule’s condition is met, but the user does not log on with a client capable of executing that rule, the action specified in the rule is deferred until the user accesses the mailbox again. The Deferred Action folder stores the action in a deferred action message. When the user logs on with a client capable of processing the rules, all of the deferred actions that the client is capable of processing are carried out. After the client processes a deferred action, the deferred action message is deleted from the Deferred Action folder.
For example, a user configures a rule that moves messages sent to a distribution list from the Inbox to a local personal folder file (.pst file). If the Outlook user is not logged on to the server when a message sent to the distribution list arrives, the action is deferred until the user logs on to the mailbox again. To ensure that the rule’s action is carried out promptly when the client accesses the mailbox, the action to move the message to a .pst file is stored in the Deferred Actions folder. When the Outlook user logs on to the mailbox again using a MAPI session, the message sent to the distribution list is moved to the local .pst file. If an Outlook Web Access client accesses a mailbox that contains deferred action messages, none of the actions are processed because Outlook Web Access is not capable of processing client-side rules. In this case, all of the deferred actions remainin the mailbox until the user accesses the mailbox using a MAPI session.