Lob - A simple API to integrate print & mail solutions into your applications.
Gmail - Gmail is available across all your devices Android, iOS, and desktop devices. Sort, collaborate or call a friend without leaving your inbox.
PostGrid - Transform your Offline Communications. Use our fully-documented REST API to send personalized letters, checks, postcards and improve address accuracy.
Yahoo Mail - Web-mail with a terabyte of free storage space & spam protection. Yahoo!
AmazingMail - Business print-mail solution
Hushmail - Full-featured email service with integrated security to safeguard your data.