How to get postfix send mail (with Gmail smtp) under macOS Catalina? I have tried everything (I guess), such as writing my sasl_passwd and editing main.cf in the /etc/postfix folder (as described in 1).  I also copied my LaunchDaemon plist with a different name to my /Library/LaunchDaemons folder (as described in 2). 

While those people managed to get postfix to send smtp Gmail messages from their terminal under Mojave and El Capitan, respectively. I haven't managed to get their solutions to work under Catalina.

Any suggestions?
Take a look at https://gist.github.com/loziju/66d3f024e102704ff5222e54a4bfd50e
Some people stated it works for them.