For More Information

You can work around the issue that is described in this topic by using dynamic distribution groups in Exchange.

In Exchange 2007, the transport component expands dynamic distribution groups to include any recipient who has attributes in Active Directory that match the group's filter. Because of this, you must make sure that a recipient who is not intended to be part of the group is not unintentionally included in the group membership filter. For example, if a recipient's attributes are modified, the recipient may match the filter criteria of the dynamic distribution group. In this scenario, the recipient would become a member of the group and would receive messages that are sent to the dynamic distribution group. To help prevent this situation, it is best to develop a well-defined and consistent account provisioning process.

One method to reduce the possibility that a recipient will unintentionally match the filter criteria is to stamp the appropriate user accounts with a particular characteristic for which they may be filtered. For example, you can configure the recipients account by using one of the Exchange custom attributes. Then, create a dynamic distribution group that has a filter for the particular custom attribute. When the Exchange transport component handles e-mail messages for the group, the transport component uses the filter to determine which users receive the e-mail messages.

To use the Active Directory Users and Computers snap-in to set a custom attribute in Exchange 2003

1. On a computer that is running Exchange 2003, start the Active Directory Users and Computers MMC snap-in.

2. Locate the user account that you want to modify, right-click the account, and then click Properties.

3. Click the Exchange Advanced tab, and then click Custom Attributes.

4. Click an attribute such as extensionAttribute1, and then click Edit.

5. In the Custom Attributes dialog box, type a value for the attribute, such as HiddenDG-1, and then click OK three times.

To use the Exchange Management Console to set a custom attribute in Exchange 2007

1. Start the Exchange Management Console.

2. Expand Recipient Configuration, and then click Mailbox.

3. Click a recipient, and then click Properties.

4. Click the General tab, and then click Custom Attributes.

5. In the Custom Attributes dialog box, type a value into the appropriate custom attribute box. For example, type HiddenDG-1 in the Custom attribute 1 box.

6. Click OK two times.

To create a dynamic distribution group filter that is based on a custom attribute in Exchange 2007

1. Start the Exchange Management Console.

2. Click Recipient Configuration, and then click New Dynamic Distribution Group in the Actions pane.

3. On the Introduction page, complete all the following fields:

   • Organizational unit By default, the Organizational unit displays the organizational unit that is set as the recipient scope. Click Browse to select the appropriate organizational unit, and then click OK.
     
     
   • Name In this box, type a name for the dynamic distribution group. The name cannot exceed 64 characters.
     
     
   • Alias In this box, type an alias for the dynamic distribution group. The alias cannot exceed 64 characters and must be unique in the forest.
     
     

4. Click Next.

5. On the Filter Settings page, define the recipient filter for the new dynamic distribution group:

   • Click Browse to select the organizational unit from which to select recipients. A dynamic distribution group contains all the recipients that are in the particular organizational unit together with any organizational units that are under the selected organizational unit.
     
     
   • Select the recipient types that you want to include in the dynamic distribution group. You can select All recipient types or The following specific types. If you select The following specific types, you must click to select at least one recipient type check box.
     
     

6. Click Next.

7. On the Conditions page, click to select the check box that corresponds to the custom attribute that you configured earlier. For example, click to select the Custom Attribute 1 equals Value check box.

8. In the Step 2 box, click the specified link to modify the custom attribute filter.

9. In the Specify Custom Attribute 1 box, type the custom attribute value that you configured earlier. For example, type HiddenDG-1. Click Add, and then click OK.

10. Click Next, click New, and then click Finish.

By default, dynamic distribution groups require senders to be authenticated. This behavior prevents external senders from sending messages to dynamic distribution groups. This default setting differs from earlier versions of Exchange. By default, in Exchange 2003, query-based distribution groups accept messages from all senders. To configure an Exchange 2007 dynamic distribution group to accept messages from all senders, you must modify the message delivery restriction settings for the dynamic distribution group. For more information how to configure message delivery restrictions, see How to Configure Message Delivery Restrictions.

For more information about how to create a dynamic distribution group, see How to Create a New Dynamic Distribution Group.