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

 process-name

    Indicates the name of the subprocess to which you want to
    connect. If the subprocess name contains spaces, special
    characters, or lower-case letters, then the subprocess name must
    be enclosed in quotation marks.