MAIL$_SEND_RESULTSPEC

    When you specify MAIL$_SEND_RESULTSPEC, MAIL$SEND_ADD_BODYPART
    returns the resultant file specification identified with MAIL$_
    SEND_FILENAME. The buffer address field of the item descriptor
    points to a buffer that receives a character string 0 to 255
    characters long.

    Specify a value from 0 to 255 in the buffer length field of the
    item descriptor.