/etc/postfix/main.cf

mydomain = saitam.int
myhostname = mailserver.$mydomain
myorigin = /etc/mailname
mydestination = $myhostname, $mydomain, localhost.saitam.int, localhost
mynetworks = 127.0.0.0/8, 192.168.1.0/24, 192.168.10.0/24, 192.168.20.0/24
home_mailbox = /home/$USER/Maildir/

# SASL parameters
smtpd_sasl_auth_enable = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_authenticated_header = yes
broken_sasl_auth_clients = yes

# 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_auth_only = yes
smtpd_tls_cert_file = /etc/ssl/certs/mailserver.saitam.int.crt
smtpd_tls_key_file = /etc/ssl/private/mailserver.saitam.com.br.key
smtpd_tls_session_cache_database = btree:${queue_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${queue_directory}/smtp_scache

#Segurança
# Aceitar ligacoes apenas a partir da rede local
smtpd_client_restrictions = permit_mynetworks,
  reject

# Clientes locais podem enviar emails para qualquer endereco
smtpd_recipient_restrictions = permit_mynetworks,
  reject_unauth_destination

# Rejeitar ligacoes de clientes que nao saibam o seu hostname
smtpd_helo_restrictions = reject_unknown_sender_domain

# Rejeitar email de dominios que nao existem
smtpd_sender_restrictions = reject_unknown_sender_domain

#relay
relayhost = [smtp.gmail.com]

# SASL SUPPORT FOR SERVERS
#
# The following options set parameters needed by Postfix to enable
# Cyrus-SASL support for authentication of mail servers.
#
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous

# Mapeamento endereços
smtp_generic_maps = hash:/etc/postfix/generic

# amavisd-new scanner
#
content_filter = amavis:[127.0.0.1]:10024
receive_override_options = no_address_mappings

mailbox_command = procmail -a "$EXTENSION"
#espaço de 1GB = 1024*1024*1024
mailbox_size_limit = 1073741824
recipient_delimiter = +
inet_interfaces = all
inet_protocols = ipv4

# indica quem irá armazenar os e-mails
virtual_transport = dovecot