With Exchange 2007 SP1, and Server 2008 Active Directory Domain Services, you may want to enable users to send emails to your security groups.  The dilema is that security groups will not show up in the Global Address List (GAL).  In order to mail-enable an AD DS security group, you must perform two steps:

1) Change the group properties to ensure that the group is a Universal, and not a Global group.  Otherwise Exchange 2007 will not see the group in order to mail-enable it.

2) Perform the following steps from within the Exchange Management Console:

1.     Start the Exchange Management Console.

2.     In the console tree, expand Recipient Configuration, and then click Distribution Group.

3.     In the action pane, click New Distribution Group. The New Distribution Group wizard appears.

4.     On the Introduction page, click Existing Group, and then click Browse.

5.     In Select Group dialog box, select the group that you want mail-enable, and then click OK.

6.     Click Next.

7.     On the Group Information page, complete the following fields:

·         Display name   By default, the display name is the same as the group name. You can modify the name in this field.

·         Alias   By default, the alias is the same as the group name. You can modify the name in this field.

8.     Click Next.

9.     On the New Distribution Group page, review the Configuration Summary. To make any configuration changes, click Back. To create the new distribution group, click New.

10.  On the Completion page, the Summary states whether the distribution group was successfully created. The summary also displays the Exchange Management Shell command that was used to create the distribution group.

11.  Click Finish.

Now, your users will be able to send notifications, etc. to their colleagues via their Outlook client and the GAL.