What are some alternatives?
When comparing Responsive Email and SlideRule UX Design Path, you can also consider the following products
Adapti - Create a unique web experience for each of your users
Weekly UX Exercise - Receive challenges top companies use to interview designers
Responsive View - Test your responsive design across different devices
Am I Responsive - see your website in multiple screen resolutions
FlowMapp - UX planning tool for creating a visual sitemap