If you use Address Book you can easily notify groups in your Address Book whenever information on your address card changes. When you select "Send Updates..." from the File menu, a pane will open listing all of your groups. To send the updated card to a particular group, put a check in front of the name of the group and click the "Send" button. Apple's Mail program will open and an email message will be sent to all members of the group with your updated card attached to the message.

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