When you set retention times for an individual mailbox or a single public folder, or for an entire information store, you can also specify that no items be deleted before the information store is backed up.

When you delete a message, Exchange Server marks the message for deletion but also marks it as hidden until it is permanently deleted from the information store. If you are using Microsoft Outlook version 8.03 or later, when you decide to retrieve a message before its retention expiration time, you can click the Deleted Item Recovery menu option on the Tools menu. The item is then visibly restored to the Inbox, and Exchange Server removes the mark for deletion.

To specify how long to retain an item:

1. To set a retention period for an individual mailbox or a public folder:
   
   NOTE: By default, deleted item retention periods that you set on individual mailboxes or public folders override the settings on the private information store.
   1. In the Exchange Server Administrator program, open the mailbox (or the public folder), and then click the Limits tab.
   2. Type the appropriate number in the Use This Value (Days) box.
2. To set a retention period for an entire private or public information store:
   1. In the Exchange Administrator program, click to expand the Server container, and then click the information store (public or private, as applicable) that you need to set the retention time for.
   2. Click the General tab, and then type the appropriate number in the Deleted item retention time (days) box.