Hey I’m not sure about docker-compose but the ghost file that would have the mail settings is located at the root of your ghost directory if you are not sure where that is you can use the command ghost ls and it will tell you you will need to edit config.production.json you will need to change the following:
After you have changed the settings you will need to restart ghost using ghost restart while you are in the ghost directory. Now you can try to send email.
Note: I’m not sure about docker-compose.yml if you should change it back or leave it as-is since I have ghost installed without docker. If sending email doesn’t work maybe try to revert the file.