Library /sys$common/syshlp/mailhelp.hlb SET-SHOW, FOLDER, Qualifiers, /NEW  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Selects the NEWMAIL folder and displays new mail messages
    received while you are in Mail. If there are no new messages,
    Mail displays the message "%MAIL-W-NONEWMAIL, no new messages".
    When a mail file other than your default mail file is open, Mail
    closes the file and opens your default mail file.