MailItem.RetentionPolicyName Property (Outlook)
Returns a String that specifies the name of the retention policy. Read-only.
Retention is enabled and disabled by an administrator for an Exchange Server on a mailbox level. The feature is available only on an Exchange mailbox with Messaging Records Management (MRM), version 2.0 or later enabled. An example of a retention policy name is "Define time interval for expiration Quick Searches".