Postfix main.cf¶

sudo nano /etc/postfix/main.cf

# Basic settings
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
biff = no
append_dot_mydomain = no
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

# Hostname und Domain
myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
relayhost = 
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all

# Mailbox format
home_mailbox = Maildir/

# SASL Authentication
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination

# Virtual domains
virtual_mailbox_domains = example.com
virtual_mailbox_maps = hash:/etc/postfix/virtual_mailbox_users
virtual_alias_maps = hash:/etc/postfix/virtual_alias_maps
virtual_mailbox_base = /var/mail/vhosts
virtual_minimum_uid = 1000
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000

# DKIM
smtpd_milters = inet:127.0.0.1:8891
non_smtpd_milters = inet:127.0.0.1:8891
milter_default_action = accept

sudo postfix reload

sudo postfix check