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.
I have used ExactTarget and Lyris and I personally like ExactTarget for medium sized or larger organizations. For small organizations an email program like iContact works nicely.
