Managing Postmark templates with Github using Travis CI or CircleCI involves storing your email templates in version control and automating their deployment to Postmark. To do this, you need to set up a Github repository for your templates, pull them from Postmark using the CLI tool, and then use a CI/CD tool like Travis CI or CircleCI to automatically push the templates to Postmark whenever you make changes to the master branch. The process involves installing the Postmark CLI tool, setting up environment variables for authentication, and creating a config file in your project root that specifies how to handle the deployment. Once set up, you can use a bash script to push your templates locally or integrate with deployment platforms like DeployBot or Buddy. It's also important to note that once your templates are stored in Github, it's recommended to avoid making changes in the Postmark web editor to prevent version conflicts.