Establishes a set of messages that you can affect as a group. You
    can copy or move this set of messages from one folder to another.
    You can also read, delete, search or extract a set of messages.
    After you enter the SET FOLDER command, you can use the following
    commands to affect the selected messages:

       COPY
       DELETE
       DIRECTORY
       EXTRACT
       FILE
       MOVE
       READ
       SEARCH

    For more information on the above commands, enter HELP command at
    the MAIL> prompt.

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

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

    The SHOW FOLDER command displays the current folder name. You
    cannot specify any parameters or qualifiers with this command.

    Format

      SET FOLDER  [foldername]

      SHOW FOLDER