Squarespace Email Campaigns - Email, but pretty.
Inkit - Direct Mail Software. Inkit is an inbound and outbound marketing platform that helps companies gain visitors, convert leads, and win sales.
Lob - A simple API to integrate print & mail solutions into your applications.
PostGrid - Transform your Offline Communications. Use our fully-documented REST API to send personalized letters, checks, postcards and improve address accuracy.
Direct Response Media Group - Direct Response Media Group offers direct mail marketing services.
PebblePost - PebblePost invented Programmatic Direct Mail® to transform real-time online activity into personalized, dynamically rendered direct mail.