Article ID: 253838 - View products that this article applies to.
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The Recipient Update Service has three system policies that are installed by default when you install Exchange 2000. They are the Mail-Enabled Recipient, Mailbox-Enabled User, and Hidden DL Membership. All have the same purpose of updating a few attributes on each entry under certain circumstances.
The idea behind the system policies is to let people write their own tool to add and edit Users, Groups, Contacts, and so on. To make the creation of these tools more simple, the Recipient Update Service takes part of the responsibility, filling gaps where a tool might have missed creating something, which would cause other services to not work properly.
For a mail-enabled recipient, there is a minimum set of attributes that is required to make all Exchange components work properly. For example, a mail-enabled entry (user, contact, group, public-folder, and so on) needs to have at least these attributes: mailNickname, legacyExchangeDN, and displayName. Without the mailNickname attribute, an object is not considered mail-enabled. After you have a mailNickname attribute, the other two attributes must be set.
Mail-Enabled Recipient PolicyIf the Recipient Update Service identifies that a new entry was added or modified that does have the mailNickname attribute, but that does not have the legacyExchangeDN or displayName attributes, it tries to create those attributes.
The displayName attribute is copied from the mailNickname attribute as is, and the legacyExchangeDN attribute goes through an algorithm that identifies the organization and administration group for this entry, and then creates a value in the following format:
Mailbox-Enabled User PolicyFor a Mailbox-Enabled User, two attributes need to be present. The first is the mailNickname attribute, and second is one of the following three attributes:
903291In this case, the Recipient Update Service tries to populate some attributes if they are not present. They are:
(http://support.microsoft.com/kb/903291/ )Recipient Update Service may overwrite the value of the homeMDB attribute for new Exchange Server 2003 users
Hidden DL Membership PolicyFor the "Hidden DL Membership" system policy, it runs not only when a new entry, such as a Security or Distribution Group, is created, but when you modify the status of the hideDLMembership attribute.
If this attribute is set to TRUE, the Recipient Update Service adds a non-canonical part to the security descriptor, which prevents anyone from viewing the "member" attribute for that entry. This will apply to any type of client searching the directory, through Messaging Application Programming Interface (MAPI) or Lightweight Directory Access Protocol (LDAP).
If the attribute is set to FALSE, it removes the non-canonical security descriptor, exposing the "member" attribute again.
For additional information about hiding group membership, click the article number below to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/253827/EN-US/ )XADM: How Exchange Hides Group Membership in the Active Directory