Establishes a set of messages that you can manipulate. You can
    copy or move selected messages from one folder to another. You
    can read, delete, search, or extract a set of messages. After you
    select a set of messages, you can then use the following commands
    to affect them:

       COPY
       DELETE
       DIRECTORY
       EXTRACT
       FILE
       MOVE
       READ
       SEARCH

    You can also use the SELECT command to move from one folder
    to another. If you select a folder that does not exist, Mail
    displays a message similar to the following:

          %MAIL-E-NOTEXIST, folder "foldername" does not exist

    Format

      SELECT  [foldername]