You could create a new group named "ALL", and copy all your contacts into
it. Then, when you create your new email, add ALL as the To: (or Cc:,
Bcc:...)
You can set up a group address with everyone in it. However, be aware that
your Internet service provider probably has a limit as to the number of
recipients on one e-mail (usually 50 or 100). You can use Paul Berkowitz'
Split Recipients script to get around that limit.