I want to use Gmail as a GUI for firstname.lastname@example.org. Im using Ubuntu 16.04 and postfix. I read this tutorial and followed steps : https://devanswers.co/configure-postfix-to-use-gmail-smtp-on-ubuntu-16-04-digitalocean-droplet/
The google mail address is email@example.com. Now, if I send email to firstname.lastname@example.org I get nothing. Also when I send email via gmail, it works, but the sent address is email@example.com.
How can I connect Gmail to postfix in order to send and receive emails only through firstname.lastname@example.org?