Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
ClickMail - ClickMail provides enterprise level email marketing software tools, providing email deliverability and authentication.
Yesmail - Yesmail provides email marketing solutions that integrate mobile, web, and social channels for marketers.
Thexyz - Secure premium email service with mobile sync apps for calendar, contacts, tasks, notes and FISMA compliant email archiving.
SendGrid - Learn why more developers choose SendGrid for their email deliverability service to send transactional emails triggered by web apps. Get started for free
GoDaddy Professional Email - GoDaddy Professional Email is a domain-based email service for businesses.