We recently joined ESPC (The Email Sender and Provider Coalition). They’re a group of responsible marketers, ISPs, ESPs, mail transfer agents, and deliverability vendors who formed to "fight spam while protecting the delivery of legitimate email." We’re really excited about this, because the ESPC has made great strides recently in pushing for authentication and responsible practices, and now we get to be a part of their discussions.
And if you’re an email marketing sender (or you’re in the email marketing business in any way), you might think about joining as well. They recently changed their name from "Email Service Provider Coalition" in order to reflect their broadened focus.