Mailu/postfix/conf/main.cf

###############
# General
###############

# Main domain and hostname
mydomain = {{ DOMAIN }}
myhostname = {{ HOSTNAME }}
myorigin = $mydomain

# Message size limit
message_size_limit = {{ MESSAGE_SIZE_LIMIT }}

# Relayed networks
mynetworks = 127.0.0.1/32 [::1]/128 {{ RELAYNETS }}

# Empty alias list to override the configuration variable and disable NIS
alias_maps =

# SQLite configuration
sql = sqlite:${config_directory}/

# Only accept virtual emails
mydestination =

# Relayhost if any is configured
relayhost = {{ RELAYHOST }}

###############
# TLS
###############

# Only one key/certificate pair is used, SNI not being supported by all
# services and not a strong requirement. Also, TLS is enforced for submission
# and smtps in master.cf.
smtpd_tls_security_level = may
smtpd_tls_cert_file=/certs/cert.pem
smtpd_tls_key_file=/certs/key.pem
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache

# Server-side TLS is hardened, it should be up to the client to update his or
# her TLS stack in order to connect to the mail server. Hardening is based on
# https://bettercrypto.org/static/applied-crypto-hardening.pdf
smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_mandatory_ciphers = high
tls_high_cipherlist = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA256:EECDH:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!IDEA:!ECDSA:kEDH:CAMELLIA128-SHA:AES128-SHA

# Outgoing TLS is more flexible because 1. not all receiving servers will
# support TLS, 2. not all will have and up-to-date TLS stack.
smtp_tls_security_level = may
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
smtp_tls_protocols =!SSLv2,!SSLv3
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# General TLS hardening
tls_ssl_options = NO_COMPRESSION
tls_preempt_cipherlist = yes

###############
# SASL
###############

smtpd_sasl_local_domain = $myhostname

# Authentication is done against dovecot, which acts as the main authention
# source
smtpd_sasl_type = dovecot
smtpd_sasl_path = inet:imap:2102
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous

###############
# Virtual
###############

virtual_mailbox_domains = ${sql}sqlite-virtual_mailbox_domains.cf
virtual_alias_maps = ${sql}sqlite-virtual_alias_maps.cf

# Mails are forwarded to Dovecot for delivery
virtual_transport = lmtp:inet:imap:2525

# In order to prevent Postfix from running DNS query, enforce the use of the
# native DNS stack, that will check /etc/hosts properly.
lmtp_host_lookup = native

###############
# Restrictions
###############

# Delay all rejects until all information can be logged
smtpd_delay_reject = yes

# Allowed senders are: the user or one of the alias destinations
smtpd_sender_login_maps = $virtual_alias_maps

# Helo restrictions
smtpd_helo_required = yes
smtpd_helo_restrictions =
   permit_mynetworks,
   reject_non_fqdn_helo_hostname,
   reject_invalid_helo_hostname,
   permit

# Sender restrictions
smtpd_sender_restrictions =
   permit_mynetworks,
   reject_non_fqdn_sender,
   reject_unknown_sender_domain,
   reject_sender_login_mismatch,
   permit

# Recipient restrictions:
smtpd_recipient_restrictions =
   reject_unauth_pipelining,
   reject_non_fqdn_recipient,
   reject_unknown_recipient_domain,
   permit_mynetworks,
   reject_unauth_destination,
   permit

###############
# Milter
###############

smtpd_milters = inet:milter:9900
milter_protocol = 6
milter_mail_macros = i {mail_addr} {client_addr} {client_name} {auth_authen}
milter_default_action = tempfail

###############
# Extra Settings
###############