Forrester updated their email marketing review methodology and published it in a new trend report titled "How to Humanize Email Marketing".
The email marketing review methodology helps marketers to evaluate the attributes and content of their email campaigns, and the effectiveness of their email program.
The revisions they made in this new version focus on humanizing the email experience. They added business criteria to test the program's customer-centricity. They also reorganized customer criteria to explicitly encompass all facets of the email conversation and added customer criteria to address market advancements.
Very interesting stuff but you do have to pay to get access to it. You can purchase this trend report here.