Lob - A simple API to integrate print & mail solutions into your applications.
MailerLite - Affordable Email Marketing Software. Get all features (Segmentation, Automation, A/B testing) for up to 1,000 subscribers & send unlimited emails for free!
PostGrid - Transform your Offline Communications. Use our fully-documented REST API to send personalized letters, checks, postcards and improve address accuracy.
Publicate - Build Beautiful Emails. Export and Send Anywhere.
AmazingMail - Business print-mail solution
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES