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.
Mailgun - A set of powerful APIs that enable you to send, receive and track email from your app effortlessly whether you use Python, Ruby, PHP, C#, Node.js or Java.
ZixArchive - ZixArchive is a cloud-based solution to collect, store and search archived emails.
MasterBase - On demand Email Marketing software
Cryoserver - Cryoserver is an all-in-one email archiving solution that empowers you to preserve your email in a tamper-evident archive, making you transform your data into a useful archive for everyday use.