Pb postfix et exchange 2007

Bonjour,
j ai le problème suivent mon postfix passe pas les mail au serveur mondiaux pour distribuer mes mails et ensuite j ai exchange qui me dit qu il a un pb de connecteur externe sauf que selui si et regler pour donner les mail a postfix

config postfix

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

myhostname = SERV.fred92g.org
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = fred92g.org
mydomain = fred92g.org
mydestination = fred92g.org, SERV.fred92g.org, localhost.fred92g.org, localhost
relayhost = 65.55.72.151
mynetworks = 127.0.0.0/8, 10.42.0.2/24
mailbox_size_limit = 5368709120
recipient_delimiter = +
inet_interfaces = all
home_mailbox = Maildir/
message_size_limit = 52428800
default_transport = smtp
transport_maps = hash:/etc/postfix/smtproutes
relay_domains = $transport_maps

merci de votre aide