You should be able to use Groups to achieve this, which at the most basic level are just mailing lists.
- Access your GAFYD control panel (e.g. https://www.google.com/a/cpanel/yourdomain.com/
- From the top navigation bar, select Users and Groups, then the Groups tab
- Create your new Group, if you just want to send emails out to the list, the "Announcement Only" would probably be the best option.
After you've created the Group, you get the option to enter the emails of members, which supports adding recipients from outside your domain.
Groups can go beyond traditional email distribution lists - they allow for a shared inbox, self-managed lists etc. There seems to be plenty of online help describing all of this via the links from the group management page.