Sending emails using Outlook 2003 and Categories

Hello All,
My client asked me if he could send an email to all his clients through Outlook 2003 that he has sorted in a certain category. I explained how he would do that (using the Actions menu, New Message to Contact, etc.). The problem now is that this process only uses the first email from each contact. In this situation, the email needs to go out to all email addresses within a contact (example, it may be a husband and wife in one contact and the email needs to reach both).

ANYWAY, does anyone know how to achieve this?

Thanks in advance, Randy.