Configure postfix as relay for macOS Sierra – Sonoma

• Source: http://www.developerfiles.com/how-to-send-emails-from-localhost-mac-os-x-el-capitan/
• Source: http://budiirawan.com/install-mail-server-mac-osx/
• Source: https://apple.stackexchange.com/questions/32228/whats-the-correctly-way-to-make-postfix-run-permanently-on-lion-not-server

1. Edit postfix configuration file

1. sudo vi /etc/postfix/main.cf
2. Ensure that the following values are set: