Zanata docker image can not send emails

For the docker images, is this about providing a mechanism to specify the email server configuration values? After all, it's all configured in standalone.xml

Yes. I think current standalone.xml configuration delegates to localhost:25 and you need to have something listening on that port. For my local dev machine with installed JBoss I have postfix installed and configured to use the Red Hat smtp as relay. For jboss running in container, we may need to provide mechanism to configure smtp in standalone.xml JBoss mail service configuration, or install postfix and configure it, or delegate to another docker container to handle all smtp traffic.

Off the top of my head, the easiest way to provide these might be using system properties. standalone.xml allows for the interpolation of system props along with a default. These could then in turn be provided when running the container.

Something like

There is still no way of specifying a specific port for SMTP and also no option to activate TLS without modifying the image.