Today in my class Sherri asked, "this mail address policy thing is neat in exchange 2007, is there an equivalent in 2003?"
     Sure is Sherri! Exchange 2003 uses a slightly different terminology on how it handles organizational address changes. It uses Recipient Policies to perform bulk SMTP address changes. Scenarios where this may be applicable is may if you purchase a new domain name and want to add it as an alias to all of your existing mailboxes.
    Here are some handy links to some MSKB and technet documents with explinations and walk-throughs!