GNU Mailman is a mailing list management software. Mailman project was started long time ago before the Millennium. Since its birth it has become the most intelligent tool for handling mailing lists ever. Huge number of companies with Fortune 500 members among them have been using Mailman for years. The new version Mailman 3 brings to us even better user experience and communication power.
Asklayer - Get real answers from your customers with Asklayers surveys, quizzes, polls and more. Works on any website with zero code and includes enterprise level features such auto-segmentation, user tagging, branching, NPS & CSAT calculation.
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Ask User - User surveys without stress
Sympa - Sympa is an open source (GNU GPL) mailing list management (MLM) software.
Doorbell.io - Collect in-app user feedback. Available on websites, iOS, and Android.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.