I am not sure how to do this in Outlook, but you can create a table with email addresses in your database, and then assign the email addresses to various groups. Then when you send email, query the table for people in that group, and attach them to the To: line using the proper syntax.
You can write a script that gets all your email addresses from Outlook and populates the table. Hmmmm, if you can do that, you can do what you want to do originally.
Try Microsoft "Windows 2000 Scripting Guide," THE best book on Windows scripting ever. (Sorry Wrox)