This adds mailhog, which is accessible on port 8025.
Add the following to your docker-compose.yml file:
mailhog:
image: yappabe/mailhog
environment:
DNSDOCK_ALIAS: mailhog.website.docker.webfolks.be
Next, add this container to your php and nginx container links.
You can now use mailhog as an smtp server, simply use 'mailhog', or whatever you named this container as host on port 1025. No credentials are needed.