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2021-09-10 | Personal | NonRoot |
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Parent:: Selfhosting, Alias Server, Cloud Server, Tools Server
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Configuring Postfix
title: Summary
collapse: open
This note goes through the installation of Postfix, an email-handling solution for servers.
style: number
Installation
Installation is simple and opens a dialogue box. Steps are described below:
- Install Postfix
sudo apt-get install -y postfix postfix-pgsql -y
- Configuration screen
Choose 'Internet Site'
- System mail name
Define a name and make a note of it for further use.
Generic configuration
title: Documentation
[Basic config](https://github.com/simple-login/app)
The basic configuration is run in detail below.
Main.cf
title: File path
/etc/postfix/main.cf
Edit the file whilst editing the following values:
- myhostname (current server)
- mydomain (associated domain)
- my origin (associated domain)
POSTFIX config file, adapted for SimpleLogin
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) biff = no
appending .domain is the MUA's job.
append_dot_mydomain = no
Uncomment the next line to generate "delayed mail" warnings
######## delay_warning_time = 4h
readme_directory = no
See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on fresh installs.
compatibility_level = 2
TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtp_tls_security_level = may smtpd_tls_security_level = may
See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
information on enabling SSL in the smtp client.
alias_maps = hash:/etc/aliases mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 240.0.0.0/24
Set your domain here
mydestination = myhostname = app.mydomain.com mydomain = mydomain.com myorigin = mydomain.com
relay_domains = pgsql:/etc/postfix/pgsql-relay-domains.cf transport_maps = pgsql:/etc/postfix/pgsql-transport-maps.cf
HELO restrictions
smtpd_delay_reject = yes 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, permit
Recipient restrictions:
smtpd_recipient_restrictions =
reject_unauth_pipelining, reject_non_fqdn_recipient, reject_unknown_recipient_domain, permit_mynetworks, reject_unauth_destination, reject_rbl_client zen.spamhaus.org, reject_rbl_client bl.spamcop.net, permit
relay domains
title: File path
/etc/postfix/pgsql-relay-domains.cf
Below is the default config for the file (replace mydomain.com with relevant value):
postgres config
hosts = localhost user = myuser password = mypassword dbname = simplelogin
query = SELECT domain FROM custom_domain WHERE domain='%s' AND verified=true
UNION SELECT '%s' WHERE '%s' = 'mydomain.com' LIMIT 1;
transport maps
title: File path
/etc/postfix/pgsql-transport-maps.cf
Below is the standard declaration of the file (replace mydomain.com with the relevant value):
postgres config
hosts = localhost user = myuser password = mypassword dbname = simplelogin
forward to smtp:127.0.0.1:20381 for custom domain AND email domain
query = SELECT 'smtp:127.0.0.1:20381' FROM custom_domain WHERE domain = '%s' AND verified=true
UNION SELECT 'smtp:127.0.0.1:20381' WHERE '%s' = 'mydomain.com' LIMIT 1;
Generic commands
Restart the service
sudo systemctl restart postfix
Allow external connections
title: Documentation
[Fwd to external smtp](https://github.com/simple-login/app/discussions/612)
Incoming
Ports
Ports (25, 465, 587) need to be opened by the firewall:
sudo ufw allow (port)/tcp
Networks
Definition of permitted networks to restrict access (in Postfix config#Main cf).
Submission/SMTPD
title: File path
/etc/postfix/master.cf
Options are coded in the file by default. Uncheck necessary directives.
SSL cert
Postfix SSL certs need to match that of the server (in Postfix config#Main cf).
SASL
Add SASL users
title: add a user
`sudo saslpasswd2 -c -u (mydomain.tld) (username)`
title: check number of users
`sudo sasldblistusers2`
Outgoing
Allow for connecting to an external SMTP - not tested.
Monitor Postfix
Monitor outgoing emails
Unfortunately there is no built-in functionality to monitor specifically outgoing emails. The following command can however be used and grans relevant info from mail.log:
sudo grep "status=sent" /var/log/mail.log | egrep -ve 'postfix/(cleanup|pickup|master|qmgr|smtpd|local|pipe)'
Monitor SMTP connections
sudo tail -f /var/log/mail.log