Just wanted to say that for a company blog post, this was really great. It's data-rich, it tells a compelling story, the site has a solid visual design, and the multiple calls to action were well placed and didn't detract from the post. I don't know this industry niche well, but I'm guessing Rafflecopter is a chief competitor. I think if they see this blog post, it'll rattle their knees a little :)
I was a little bit annoyed by them calculating the ROI without including the internal costs of writing copy etc. - any ROI calculation that regards staff salaries as a sunk cost is going to be basically useless.
The flip side, of course, is they also don't guesstimate future revenue from new customers attracted by likes generated by the promotion, or from increased engagement (or revenue lost because people made purchases they were going to make anyway but at a 10% discount, or because they were annoyed by the promotion and unsubscribed). Even direct marketing often is more data alchemy than data science :)