[Exim] hiding the internal list exploder

i have some majordomo mailing lists. they are on a secondary domain name of
the host. i.e., the host is psg.com and the list is idn@???.

spammers send to idn-data@{both} i want to close that off.

per a good-looking hint from Richard Welty <rwelty@???>

the aliases looks like

in majordomo.ext
    idn: "|/usr/local/majordomo/wrapper resend -l idn idn-data"
    idn-request: "|/usr/local/majordomo/wrapper majordomo -l idn"
    idn-list-request: idn-request
    idn-owner: idn-approval
    owner-idn: idn-owner
    owner-idn-data: idn-owner
    idn-approval: user@???

in majordomo.int
    idn-data: :include:/usr/local/majordomo/lists/idn

and i have

    majordomo_ext:
      driver = aliasfile
      file = /usr/local/majordomo/lists/majordomo.ext.db
      search_type = dbm
      file_transport = mlist_file
      pipe_transport = address_pipe
      user = lserv
      group = majordom

    majordomo_int:
      driver = aliasfile
      file = /usr/local/majordomo/lists/majordomo.int.db
      search_type = dbm
      file_transport = mlist_file
      pipe_transport = address_pipe
      user = lserv
      group = majordom
      condition="{if eq ($received_protocol} {local} {true} {false} }"

and

    ietf_local:
      driver = smartuser
      local_parts = /usr/local/etc/exim/ietf.local
      domains = ops.ietf.org
      new_address = ${local_part}@???

where /usr/local/etc/exim/ietf.local has idn but not idn-data

and i get some very strange behavior

    rip.psg.com:/usr/home/randy> telnet psg.com smtp
    Trying 147.28.0.62...
    Connected to psg.com.
    Escape character is '^]'.
    220 psg.com ESMTP Exim 3.33 #1 Tue, 18 Dec 2001 17:31:08 -0800
    helo rip.psg.com
    250 psg.com Hello rip.psg.com [147.28.0.39]
    mail from: randy@???
    250 <randy@???> is syntactically correct
    rcpt to: idn@???
    250 <idn@???> verified                   -- cool
    rcpt to: idn-data@???
    550 <idn-data@???> Unknown local part    -- yes!
    rcpt to: idn@???
    250 <idn@???> verified                        -- ok, i guess
    rcpt to: idn-data@???
    250 <idn-data@???> verified                   -- yikes!!!!!
    quit
    221 psg.com closing connection
    Connection closed by foreign host.

clues?

randy