confirm looping. How to stop it?

Hello tmda'ers.

I'm trying to work through a problem with a new installation of tmda and
could use your advice.  This particular server has been running courier
+ dspam + maildrop successfully for quite some time.  Now, I wish to add
tmda as the last step.  Anything not filtered out by the spam filter, or
mailing list filter should be subject to tmda.

The courier default deliver instructions system wide are
| /usr/local/bin/dspam --deliver=innocent,spam --user $USER

Dspam then calls maildrop via (dspam.conf):
TrustedDeliveryAgent "/usr/lib/courier/bin/maildrop -d %u"

I have never used a .courier file, so I created one in my home directory
as:
| /usr/local/bin/dspam --deliver=innocent,spam 

I also created a .courier-default file by symbolically linking
to .courier, so that email to rduz-confirm* could be successfully
delivered.

my ~/.mailfilter is very long because I filter for lots of email lists,
but per the instructions, I have added these lines near the beginning, 
  import SENDER  
  import RECIPIENT
  import EXTENSION

and this at the end.
  to "| /usr/local/bin/tmda-filter"

For the ~/.tmda/config file config file, I am using the one from
contrib.  I set MAIL_TRANSFER_AGENT to "qmail" and DELIVERY to
"~/Maildir/"

In this configuration, email from an unknown source is sent a
confirmation message.  Rather than accepting the confirmation, and
allowing the message in, another confirmation for the reply is
generated.  This continues over and over again.  Confirmations are never
recognized as confirmations.  They are instead seen as new requests, and
erroneously treated as such.

I've been following the instructions in
http://wiki.tmda.net/TroubleShooting, and I've read some traffic on the
e-mail list archives about a patch from 2001, but I suspect that it has
long been integrated.

The main interesting bit in the maillog is that tmda-filter is exiting
with code 99, even on a response to a confirm request.  

TMDA Version:
TMDA/1.1.5 "Fettercairn" (Python/2.3.5 on
Linux-2.4.20-31.9smp-i686-with-redhat-9-Shrike)

Tarball, installed from latest release today.

MTA is courier, and running tmda as last step from maildrop.

What am I doing wrong?

Thank you.

Regards,
Rich