Probleme potsfix

Bonsoir(jour),à tous.
Mon probléme que je voudrais utiliser postfix afin de recevoir et envoyer des messages de l'exterieur.J'ai un compte chez no-ip rachsec.no-ip.biz,mais le probléme que je recoi mais email qu'en local,mais lors de l'essai de l'envoi a l exterieur il m'affiche un message d'ereur.

voila mon main.cf:

# 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 = r00t.rachsec.no-ip.biz
mydomain = rachsec.no-ip.biz
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = $mydomain
mydestination = rachsec.no-ip.biz, r00t.rachsec.no-ip.biz, localhost.localdomain, localhost
relayhost = rachsec.no-ip.biz
mynetworks = 192.168.2.0/22, 127.0.0.0/8
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
home_mailbox = Maildir/

et merci pour votre atention ;)