Understanding Recipients
Central to any messaging system are the people and resources that receive messages. An individual may receive a message from a coworker, or a public folder may receive a message from a participant in a particular discussion.
Although messages are received by people, the term recipients refers to Microsoft Active Directory® directory service objects, not people. Recipients are Active Directory objects that have messaging capabilities. However, the object itself does not receive messages. The messages are not stored in Active Directory. Instead, they can reside in a mailbox on an Exchange server, in a public folder, or in another messaging system.
People access messages that are sent to them by using a client application. Examples of client applications include Microsoft Outlook®, Outlook Web Access, and Outlook Mobile Access. Each of these clients receives notification when a new message arrives and receives pointers to the location of the message, so that the message can be opened and read.
The following scenario explains the difference between the person who receives e-mail messages and Active Directory objects. Carole, a member of the marketing team, has a user account that prompts her to type her user name and password to log on to her computer and her company's network. After logging on, she has access to several network resources. One of these resources is her Exchange mailbox. Carole accesses her mailbox with an e-mail client, Outlook 2002. Outlook queries her Exchange mailbox and presents Carole a list of messages in her Outlook Inbox. When Carole opens one of these messages, Outlook retrieves the contents of the message from the message store on the Exchange server that houses her mailbox.
As shown in the following figure, there is a recipient that is an Active Directory user object named carole. Mail that is addressed to carole is stored in an associated mailbox on an Exchange server. When the correct credentials are sent to the domain controller for user object carole, the contents of the mailbox become available to the e-mail client.
Users authenticate to Active Directory and then use mail clients to access the contents of their Exchange mailbox
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In Exchange, the term recipient refers to an Active Directory object that is mailbox-enabled or mail-enabled. Mailbox-enabled recipients can send, receive, and store messages. Mail-enabled recipients can only receive messages.
The following table describes the Active Directory objects that can be Exchange recipients.
Exchange recipient objects
| Active Directory object | Type of recipient | Description |
|---|---|---|
Users |
Mailbox-enabled Mail-enabled |
Users can log on to networks and access domain resources. Users can be added to groups and appear in the global address list (GAL). Mailbox-enabled users can send and receive messages and store messages on their Exchange server. Mail-enabled users can receive messages at an external e-mail address only. They cannot send or store messages on Exchange. |
InetOrgPerson |
Mailbox-enabled Mail-enabled |
A user object that has had its properties extended to improve compatibility with directory services that use the InetOrgPerson object. As a recipient, InetOrgPerson has the same characteristics as a user object. To mail-enable or mailbox-enable an InetOrgPerson object, you must have a Microsoft Windows Server™ 2003 domain controller and an Exchange 2003-only environment (no servers running Exchange 2000 Server or Exchange Server version 5.5). |
Contacts |
Mail-enabled |
Contacts are objects that contain information about people or organizations outside the Exchange organization. Mail-enabled contacts can receive e-mail messages at an external e-mail address. They can be added to distribution lists and appear in the GAL. Contacts cannot access network resources. |
Groups |
Mail-enabled |
A group is an object that can contain users, InetOrgPerson objects, contacts, public folders, and other groups. |
Query-based distribution groups |
Mail-enabled |
Query-based distribution groups are similar to standard distribution groups, except that they use an LDAP query to dynamically build the group membership. The query is run when a message is sent to the query-based distribution group. When you create a query-based distribution group, you select the criteria for the query. |
Public folders |
Mail-enabled |
Public folders are repositories for messages and other files that can be accessed by users on the network. |
Note
Although public folders are recipients, they are different from the other recipient types mentioned here. For more information about public folders, see "Managing Mailbox Stores and Public Folder Stores."