Distribution List

  Choose Distribution List...  from the To or CC pop-up menu
  to send a message to a distribution list.

  A dialog box is displayed in which you choose the name of the
  distribution list to be used.

  Distribution lists are not created within Mail.  Use an editor,
  such as EVE, to create your distribution list files.  When
  naming distribution list files, use a DIS file type since that is
  what Mail looks for by default.

  Additional topics:

  *   Using a Distribution List

  *   Using a File Selection Dialog Box