According to a recent Forrester report 12.09, ExactTarget and Responsys lead the email service providers in their 69 criteria study of email marketing service providers.
Acxiom Alterian BlueHornet ClickSquared Datran Media e-Dialog Emailvision Epsilon ExactTarget Experian Marketing Services Lyris Responsys Silverpop Yesmail Zeta Interactive
A copy of the full report can be found here.
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