In Forrester's 34-criteria evaluation of email marketing vendors, we identified the nine most significant providers — Acxiom, Epsilon, Experian Marketing Services, Oracle Responsys, Salesforce ExactTarget, Silverpop, StrongView, Yesmail Interactive, and Zeta Interactive — from a pool of 33 and researched, analyzed, and scored them. This report details our findings about how well each vendor fulfills our criteria, and where they stand in relation to each other, to help interactive marketing professionals select the right partner for their email marketing efforts.