Best settings for antispam / Postfix

Hello,

last week my mail server has been put on blacklist, mainly because of bounces and automatic replies (holidays ...).
I've changed a few settings and I'm not sure they are very good.
I use postfix 1.1.11 on a debian server (Linux mail 2.2.19) and exchange 2003.

Here is the result of postconf -n:

alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
allow_percent_hack = no
biff = no
body_checks = pcre:/etc/postfix/body_checks
canonical_maps = hash:/etc/postfix/canonical
command_directory = /usr/sbin
config_directory = /etc/postfix
content_filter = avcheck
daemon_directory = /usr/lib/postfix
debug_peer_level = 2
default_destination_concurrency_limit = 10
delay_warning_time = 2h
disable_vrfy_command = yes
header_checks = pcre:/etc/postfix/header_checks
local_destination_concurrency_limit = 2
maps_rbl_domains = cbl.abuseat.org, bl.spamcop.net, dnsbl.sorb.net, zen.spamhaus.org
maximal_queue_lifetime = 5d
message_size_limit = 35971520
mydestination = $myhostname, localhost.$mydomain, $mydomain
mydomain = xxx.fr
myhostname = mail.xxx.fr
mynetworks = 192.168.0.0/24, 127.0.0.0/8, 172.16.0.0/24
myorigin = $mydomain
program_directory = /usr/lib/postfix
relay_domains = xxx.fr xxx.com
smtp_data_xfer_timeout = 240s
smtpd_banner = $myhostname ESMTP $mail_name
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks, reject_invalid_hostname, check_client_access hash:/etc/postfix/access_sender
smtpd_recipient_restrictions = reject_invalid_hostname, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, reject_unauth_destination, check_recipient_access regexp:/etc/postfix/access, check_sender_access hash:/etc/postfix/access_sender, reject_maps_rbl, permit
smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/access_sender, reject_maps_rbl, reject_unknown_sender_domain, permit
swap_bangpath = no
transport_maps = hash:/etc/postfix/transport
 
body_checks:
#Pflogsumm log Accept
/^ {6,11}[[:digit:]]{1,6}[ km] /    OK
/^[> ]*Received: +from +(relay-2\.mail\.demon\.net)/ REJECT
/^[> ]*Received: +from +(relay-1\.mail\.demon\.net)/ REJECT
/^[> ]*Received: +from +(brutele\.net)/ REJECT
/^[> ]*Received: +from +(bacgroup\.com)/ REJECT
# Some basic antivirus checks
/^Content-Disposition:attachment;filename=\".*\.(doc|zip|exe|xls|jpg|gif)\.(pif|bat|com|exe|lnk)\"$/   REJECT
/^Content-Disposition:attachment;filename=.*\.(doc|zip|exe|xls|jpg|gif)\.(pif|bat|com|exe|lnk)$/       REJECT
# Common virus extensions that most people wouldnt send legitamitely
/(filename|name)=".*\.(asd|chm|hlp|hta|ocx|pif|bat)"/        REJECT
/(filename|name)=.*\.(asd|chm|hlp|hta|ocx|pif|bat)/        REJECT
/(filename|name)=".*\.(scr|shb|shs|vb|vbe|vbs|wsf|wsh)"/        REJECT
/(filename|name)=.*\.(scr|shb|shs|vb|vbe|vbs|wsf|wsh)/        REJECT
/(filename)=".*\.(com)"/                           REJECT
/(filename)=.*\.(com)/                           REJECT
# Bugbear virus
/(filename|name)=".*\.(.*)\.(pif|scr|bat|com|exe|lnk)"$/        REJECT
/(filename|name)=.*\.(.*)\.(pif|scr|bat|com|exe|lnk)$/        REJECT

header_checks:
/^Subject.* CNN Alerts: My Custom Alert */ REJECT
/^Subject.* Inscrivez-vous a Fiesta Club */ REJECT
/^Subject.* First Casino est le leader français des casinos en ligne */ REJECT
/^Subject.* Demandez votre bonus GRATUIT */ REJECT
/^Subject.* I LOVE YOU */ REJECT
/^Subject.* viagra */ REJECT
/^Subject.* cialis */ REJECT
/^Subject.* penis */ REJECT
/^Subject.* life ins */ REJECT
/^Subject.* your prescription */ REJECT
/^Subject.* blue pill */ REJECT
/^Subject.* health insurance */ REJECT
/^Subject.* order med */ REJECT
/^Subject.* rejuvenate */ REJECT
/^Subject.* prescription */ REJECT
/^Subject.* get med */ REJECT
/^Subject.* xanax */ REJECT
/^Subject.* save on term*/ REJECT
/^Subject.* lose weight */ REJECT
/^Subject.* all-natural */ REJECT
/^Subject.* inches */ REJECT
/^Subject.* check it out */ REJECT
/^Subject.* check this out */ REJECT
/^Subject.* degree program */ REJECT
/^Subject.* enhanced pill */ REJECT
/^Subject.* cash out */ REJECT
/^Subject.* popish */ REJECT
/^Subject.* dogwood */ REJECT
/^Subject.* cokleblur*/ REJECT
/^Subject.* blurb */ REJECT
/^Subject.* all drugs  */ REJECT
/^Subject.* your willy */ REJECT
/^Subject.* big money */ REJECT
/^Subject.* masochist */ REJECT
/^Subject.* pain medication */ REJECT
/^Subject.* get the job */ REJECT
/^Subject.* pnarmacy */ REJECT

Do you see any possible improvments?

Regards,
Gilles