Mailmeteor - Send hundreds of personalized emails with Gmail.
Lob - A simple API to integrate print & mail solutions into your applications.
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
PostGrid - Transform your Offline Communications. Use our fully-documented REST API to send personalized letters, checks, postcards and improve address accuracy.
Interseller - Interseller helps find contact information, reach out to them with email automation and syncs it all into your database.
AmazingMail - Business print-mail solution