Install and Configure Postfix on Gentoo Linux

Step 1 – Install Postfix

emerge --ask mail-mta/postfix
rc-update add postfix default
rc-service postfix start

Step 2 – Basic configuration (/etc/postfix/main.cf)

# Network
myhostname = mail.example.com
mydomain   = example.com
myorigin   = $mydomain
inet_interfaces = all
inet_protocols = all

# Relay and destination
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mynetworks    = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128

# TLS (after obtaining a certificate)
smtpd_tls_cert_file = /etc/ssl/certs/mail.example.com.crt
smtpd_tls_key_file  = /etc/ssl/private/mail.example.com.key
smtpd_tls_security_level = may
smtp_tls_security_level  = may

# Submission (port 587)
# Uncomment relevant lines in /etc/postfix/master.cf

# Mailbox
home_mailbox = Maildir/
mailbox_size_limit = 0
message_size_limit = 52428800

# Anti-spam basics
smtpd_helo_required = yes
smtpd_recipient_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_unauth_destination

Step 3 – Reload

postfix check
systemctl reload postfix 2>/dev/null || rc-service postfix reload 2>/dev/null || rcctl reload postfix

Step 4 – Send a test email

echo "Test body" | mail -s "Test subject" [email protected]
tail -f /var/log/maillog 2>/dev/null || tail -f /var/log/mail.log