Establishes (or opens) another file as the current mail file. By
    default, your mail file is MAIL.MAI. Use the COPY command, the
    FILE command, or the MOVE command to create other mail files (for
    example, JOKES.MAI or HISTORY.MAI). You can then use the SET FILE
    command to open the mail files.

    When you enter the SET FILE command, the WASTEBASKET folder of
    the current mail file is emptied (if AUTO_PURGE is set), the file
    is closed, and the specified (alternate) file is opened.

    The SHOW FILE command displays the name of the mail file that is
    currently open.

    Format

      SET FILE  file-name

      SHOW FILE