By assigning a retention category to items at the time they are archived, it is possible to categorize stored items. This categorization makes it easier to retrieve items because it is possible to search by category.

A retention category also specifies a retention period, which is the minimum amount of time after its last modification date that an item must be retained. For mail messages, the Retention Period is the time since the message was received. For documents, it is the time since the document was last modified.

Users can select retention categories from the list and assign them to items in their mailboxes. When Enterprise Vault archives an item, it is stored with the appropriate retention category.

If you later modify a retention category, the changes are retrospective. For example, if you have a retention category called "Customer Accounts" with a retention period of 5 years and you change it to 10 years, then items that have been already archived with the "Customer Accounts" retention category are retained for a minimum of 10 years.

You can create as many retention categories as you require. You can also modify the standard retention categories to suit your own needs. If you modify a retention category, the changes apply to all items that are archived with that retention category and also to all items that have already been archived with that retention category.

Each retention category has a retention period, which indicates how long you want to retain the items that are archived with this retention category. When the retention period has elapsed, Enterprise Vault can automatically delete the items. See the Storage Expiry tab in Site Properties to set up expiry.