Sanebox - SaneBox is a cloud-based service that allows users to filter and manage their emails.
Flexmail Solution - Professional email marketing with powerful and easy-to-use features
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Mizmoz - Easy-to-use, state of the art, email service provider dedicated to support growing businesses.
Ebsta - Capture every email and business contact inside Salesforce.
Marble Responsive Email Designer - Marble helps you design beautiful and mobile-friendly emails and newsletters.