An example of how to leverage transactional templates and substitutions using SendGrid's PHP library
In email.php, create the customers array, insert sender/templateID info, and then...
Build the image
docker build -t TAG_NAME .
Run the container (you must have your API key saved as an env var called $SG_API_KEY)
docker run -it --rm -v "$(pwd)"/scripts:/usr/src/app -e SG_API_KEY={$SG_API_KEY} --name NAME TAG_NAME