Hey Stefano. The twitter Lead Generation Card makes it easy for people to express interest in what your business offers – they can seamlessly and securely share their email address without leaving Twitter or having to fill out a cumbersome form.
Lead generation cards work directly within your promoted tweet to collect users’ contact information in exchange for your offer. Twitter lead generation cards increase conversion rates by capturing in-app form-fills from your followers. Think of them as embedded landing pages within your tweets, except they’re much more concise and require much less work from your followers.
More info: http://www.niemanlab.org/2014/06/convert-your-twitter-followers-to-email-subscribers-with-a-twitter-lead-generation-card/
Many newsletter systems are compatible with lead generation card also they give information for setting up. Hope you can help us to make it compatible. If you have questions feel free to ask 😉