MailUp is already integrated with the most popular social networks in two ways: (a) users can sign up for a newsletter using their social network login; (b) you can easily add social network icons to any message to let recipients share the message. What we are working on is:
When you create or edit a message using the built-in editor in your MailUp console, you can very easily add social network icons anywhere in the message. Recipients will be able to click on any of those icons to share the message with their friends. A link to the Web version of the message is included in the post.