[exim] Mailman with exim4 on Debian Sarge

Hello,
I installed and configured mailman on Debian Sarge running apache2 and exim4.
I set up a list and the list adminstrator / owner can post to the list from a
remote client. I am pretty sure that the mailman config is right and that
there is a problem with the exim4 config. Non local subscribers cannot post
to the list. The Exim4 log always says that relay is not permitted.

/var/log/exim4/mainlog:
2006-09-01 00:00:52 H=mailout01.sul.t-online.com [194.25.134.80]
F=<k.oliver@???> rejected RCPT <news@???>: relay
not permitted

Here are parts of my exim4 config:
[..]
# On Debian systems, the main binary is installed as exim4 to avoid
# conflicts with the exim 3 packages.
exim_path = /usr/sbin/exim4

# Macro defining the main configuration directory.
# We do not use absolute paths.
.ifndef CONFDIR
CONFDIR = /etc/exim4
.endif

# This sets a macro DC_minimaldns if dc_minimaldns=true. If
# dc_minimaldns=false, this expands to an empty line.
.ifndef DC_minimaldns
DEBCONFminimaldnsDEBCONF
.endif

# Create other macros from Debconf. Macros created here are used in
# other places in exim config.
.ifndef DC_visiblename
DC_visiblename=DEBCONFvisiblenameDEBCONF
.endif

# Create domain and host lists for relay control
# '@' refers to 'the name of the local host'

.ifndef MAIN_LOCAL_DOMAINS
MAIN_LOCAL_DOMAINS = DEBCONFlocal_domainsDEBCONF
.endif
domainlist local_domains = MAIN_LOCAL_DOMAINS

.ifndef MAIN_RELAY_TO_DOMAINS
MAIN_RELAY_TO_DOMAINS = DEBCONFrelay_domainsDEBCONF
.endif
domainlist relay_to_domains = MAIN_RELAY_TO_DOMAINS

.ifndef MAIN_RELAY_NETS
MAIN_RELAY_NETS = DEBCONFrelay_netsDEBCONF
.endif
hostlist relay_from_hosts = 127.0.0.1 : ::::1 : MAIN_RELAY_NETS

# Specify the domain you want to be added to all unqualified addresses
# here. Unqualified addresses are accepted only from local callers by
# default. The recipient_unqualified_hosts option can be used to permit
# unqualified addresses from remote sources.
# If qualify_domain is not set, the primary_hostname value is used for
# qualification.
# The ifdef bracket makes sure that an empty debconf value is correctly
# translated to "unset".
.ifdef DC_visiblename
qualify_domain = DC_visiblename
.endif
[..]
# Home dir for your Mailman installation -- aka Mailman's prefix
# directory.
# By default this is set to "/usr/local/mailman"
# On a Red Hat/Fedora system using the RPM use "/var/mailman"
# On Debian using the deb package use "/var/lib/mailman"
# This is normally the same as ~mailman
MAILMAN_HOME=/var/lib/mailman
#
# User and group for Mailman, should match your --with-mail-gid
# switch to Mailman's configure script.
# Value is normally "mailman"
MAILMAN_USER=list
MAILMAN_GROUP=daemon
#
# Domains that your lists are in - colon separated list
# you may wish to add these into local_domains as well
domainlist MAILMAN_DOMAINS=news.server.windfinder.com
#
# -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#
# These values are derived from the ones above and should not need
# editing unless you have munged your mailman installation
#
# The path of the Mailman mail wrapper script
MAILMAN_WRAP=MAILMAN_HOME/mail/mailman
#
# The path of the list config file (used as a required file when
# verifying list addresses)
MAILMAN_LISTCHK=MAILMAN_HOME/lists/${lc::$local_part}/config.pck
[..]
begin routers

mailman_router:
driver = accept
require_files = MAILMAN_HOME/lists/$local_part/config.pck
local_part_suffix_optional
local_part_suffix = -bounces : -bounces+* : \
-confirm+* : -join : -leave : \
-owner : -request : -admin
transport = mailman_transport
[..]
begin transports

mailman_transport:
driver = pipe
command = MAILMAN_WRAP \
'${if def:local_part_suffix \
{${sg{$local_part_suffix}{-(\\w+)(\\+.*)?}{\$1}}} \
{post}}' \
$local_part
current_directory = MAILMAN_HOME
home_directory = MAILMAN_HOME
user = MAILMAN_USER
group = MAILMAN_GROUP

Any idea how to configure Exim4 to allow posting to mailing list for
subscribers like someone@????