utiliser basiquement la même conf qu'un outlook

sudo apt-get install postfix sasl2-bin libsasl2-2 libsasl2-modules

emacs /etc/postfix/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 (Debian/GNU)
biff = no
appending .domain is the MUA's job.
append_dot_mydomain = no
delay_warning_time = 2h
bounce_notice_recipient = postfix-errors@yourdomain.com
delay_notice_recipient = postfix-errors@yourdomain.com
error_notice_recipient = postfix-errors@yourdomain.com
readme_directory = no
myhostname = yourdomain.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydomain = yourdomain.com
myorigin = $mydomain
mydestination =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = 127.0.0.1
inet_protocols = ipv4
SSL parameters - these are used when sending mail via 1and1 to ensure the connection's secure.
smtp_use_tls=yes
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_sasl_tls_security_options = noanonymous
tls_random_source = dev:/dev/urandom
SASL Settings - These are the setting to authenticate with 1and1.  Basically it passes a username & password.
smtp_sasl_auth_enable = yes
relayhost=[auth.smtp.1and1.fr]:587
smtp_sasl_password_maps=hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous

apres on crée le fichier de mot de passe :

emacs /etc/postfix/sasl_passwd
[auth.smtp.1and1.fr]:587 name@yourdomain.com:password

chown root.root /etc/postfix/sasl_passwd
chmod 600 /etc/postfix/sasl_passwd
postmap sasl_passwd
postfix check
/etc/init.d/postfix restart
apt-get install mailutils

tester avec : mail email@email.com vérifier les logs : tail -f /var/log/mail.log