ClickMail - ClickMail provides enterprise level email marketing software tools, providing email deliverability and authentication.
SendGrid - Learn why more developers choose SendGrid for their email deliverability service to send transactional emails triggered by web apps. Get started for free
JangoMail - Description of the software: JangoMail software is a fantastic tracking solution system that many businesses can utilize for their marketing.
PostageApp - PostageApp is an email management service that makes it easy to design, deliver, and manage all of the email that websites or applications send.
MasterBase - On demand Email Marketing software
Pobox - Pobox provides email forwarding, filtering, and mailboxes.