Klaviyo - Klaviyo helps brands own the customer experience, grow higher-value relationships, and deliver more personalized marketing experiences across email, mobile, and web.
Lob - A simple API to integrate print & mail solutions into your applications.
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
PostGrid - Transform your Offline Communications. Use our fully-documented REST API to send personalized letters, checks, postcards and improve address accuracy.
TargetBay - TargetBay is a complete eCommerce revenue generation platform.
AmazingMail - Business print-mail solution