I write a lot about email marketing campaigns and best practices... in part because it is such a vital, under-discussed lever for marketers (primarily for engagement / retention). But also because I get so many emails that it's easy to compare effective ones against the junky ones (which are the vast majority). I pay attention to emails from movie-rental company Redbox because they are intelligent and well crafted.

Redbox runs email promotions that have a clear purpose. I wrote before that about the email campaign / offer aimed at validating email addresses - it was smart because it rewarded an action that was worth longer-term value (free movie for an email validation).

Redbox has run similar offers / campaigns for Facebook Likes.

Below is a 2-for-1 email promotion. Seems like a great deal - and it is: three movies for <$2/night? Of course Redbox knows that the third movie is either no-cost to them OR results in greater value (from late return fees associated with incremental rental days... after all, is watching three movies in a night possible?). And the email arrives on a Friday (smart: if you're going to rent three movies, it should be for the entire weekend).

I love the fact that Redbox is eager to reward users who do a little work: whether its validate an email, like the company of Facebook or rent a couple movies.