This will describe how to make your openSUSE machine send e-mail via reliable relayhost of your choice using Postfix. I will use gmail as an example.

  1. Installing required packages

    zypper in postfix cyrus-sasl libsasl2-3 cyrus-sasl-plain cyrus-sasl-gssapi

  2. Configure Postfix:

    cp /etc/postfix/main.cf{,_bak}
cat <<EOT >> /etc/postfix/main.cf
compatibility_level = 3.6
queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/lib/postfix/bin/
data_directory = /var/lib/postfix
mail_owner = postfix
inet_interfaces = 127.0.0.1,::1
setgid_group = maildrop
  
relayhost = [smtp.gmail.com]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = lmdb:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/ca-bundle.pem
EOT

  3. Create sasl_passwd file and

    echo "[smtp.gmail.com]:587 $USER@gmail.com:$PASSWORD" >> /etc/postfix/sasl_passwd
postmap /etc/postfix/sasl_passwd

  4. Restart the systemd service

    systemctl enable --now postfix.service

  5. Test it out

    echo "This is just a test." | mail -r "quiiicq@gmail.com" -s "A test of the system mail system" -Ssendwait pdostal@pdostal.cz

    The -Ssendwait makes the mail program wait until the e-mail is really submited to the queue instead of doing it in background.

linux