Config postfix smarthost¶

smarthost with any smtp-server¶

have a look at: https://www.alldiscoveries.com/configuring-relayhost-smarthost-ubuntu-server-22-04-lts-with-gmail-or-another-email-server-via-postfix/

smarthost with local mailcow-dockerized¶

currently we are using Ubuntu only as a base for mailcow.
So things are a bit different here, see also: https://docs.mailcow.email/post_installation/firststeps-local_mta/

install postfix and mail¶

sudo apt install mailutils

configure postfix¶

sudo vim /etc/postfix/master.cf

#smtp      inet  n       -       -       -       -       smtpd

sudo vim /etc/postfix/main.cf

# as per https://docs.mailcow.email/post_installation/firststeps-local_mta/
relayhost = 172.22.1.1
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
inet_interfaces = loopback-only
relay_transport = relay
default_transport = smtp

additionally we need to know the server and email-address as well as the password to use

vim /etc/postfix/sasl_passwd

mail.example.com:587     mailadr@example.com:password

The above server hostname and port must exactly match the value for "relayhost" in /etc/postfix/main.cf.

Generate a postfix lookup table from the previous file

postmap hash:/etc/postfix/sasl_passwd

Test the lookup table, if all is good then the following will return the specified username:password

postmap -q mail.example.com:587 /etc/postfix/sasl_passwd

next is to bind the local username to the email-address. You may also have a look into /etc/aliases and check who's mail are sent to whom.

vim /etc/postfix/canonical

root     mailadr@example.com

The above email-address must exactly match the email-address in sasl_passwd.

Generate a postfix lookup table from the previous file

postmap hash:/etc/postfix/canonical

Make sure that sasl_passwd and sasl_passwd.db files are readable/writeable only by root

chmod 600 /etc/postfix/sasl_passwd
chmod 600 /etc/postfix/sasl_passwd.db

Add postfix to be started at boot

systemctl enable postfix

maybe necessary¶

sudo mkfifo /var/spool/postfix/public/pickup