When should I use this main.cf?
Use it to restore a missing default, confirm what shipped, or diff against your current Postfix config.
# 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 $mail_name (Ubuntu)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
readme_directory = no
# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 3.6 on
# fresh installs.
compatibility_level = 3.6
# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level=may
smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level=may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = d6be24efb3b7
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = $myhostname, d6be24efb3b7, localhost.localdomain, , localhost
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
curl https://exampleconfig.com/api/v1/config/original/66885213eaa0b8e20c54c8ac477cd736?hint=main.cf
wget -O main.cf https://exampleconfig.com/api/v1/config/original/66885213eaa0b8e20c54c8ac477cd736?hint=main.cf
<prompt><role>DevOps agent</role><source url='https://exampleconfig.com/api/v1/config/original/66885213eaa0b8e20c54c8ac477cd736?hint=main.cf' /><config><app>Postfix</app><os>Ubuntu 22.04 LTS (Jammy Jellyfish)</os><location>/etc/postfix/main.cf</location><lines>46</lines><md5>66885213eaa0b8e20c54c8ac477cd736</md5><sha256>e7cda2fb74b4de15c8225a74d55e73c5d14d4a3503bca1175a0eb433fed4eeed</sha256></config></prompt>
Paste into Claude, ChatGPT, or any AI assistant.
sudo apk add postfix
sudo apt update && sudo apt install postfix
sudo yum install postfix
sudo apt update && sudo apt install postfix
When should I use this main.cf?
Use it to restore a missing default, confirm what shipped, or diff against your current Postfix config.
How do I restore Postfix defaults?
Download the file, back up the current one in /etc/postfix/main.cf, replace it, then reload or restart Postfix.
Is main.cf safe for production?
It is the vendor default for Ubuntu 22.04 LTS (Jammy Jellyfish). Treat it as a baseline and review security and performance settings before production use.
How does this differ from other OS versions?
Defaults vary by distro and version. This copy matches Ubuntu 22.04 LTS (Jammy Jellyfish).
Can I use this for Postfix troubleshooting?
Yes. Diff it against yours to find drift, then restore only the sections you need.