Hi Bill,
Under this scenario, you can set up 'Simple Domain Sharing for SMTP Email Addresses'.
Simple Domain Sharing for SMTP Email Addresses:
http://community.office365.com/en-us/wikis/exchange/simple-domain-sharing-for-smtp-email-addresses.aspx
http://community.office365.com/en-us/wikis/exchange/simple-domain-sharing-for-smtp-email-addresses.aspx
Thanks,
Edward Qu
Edward Qu