Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
Lookback - See how people really use your app
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
Dovetail - Mobile Cloud-Based Dental Software
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Preely - Remote user testing and rapid prototyping