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

 foldername

    When using SET FOLDER, specifies the name of the folder from
    which messages will be selected.

    If you omit the folder name when specifying SET FOLDER, the
    folder used is determined in the following order:

    1. The current folder is used, if any (unless the /NEW qualifier
       is specified).

    2. The NEWMAIL folder is used if:

       o  You specify the /NEW qualifier.

       o  You omit selection qualifiers and you have new mail.

    3. The MAIL folder is used.