Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
Salesflare - Simply powerful CRM. Automates your data to build better relationships and make more sales.
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
17hats - The all-in-one business system for entrepreneurs.
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
LinkPoint Connect - LinkPoint Connect: Desktop Edition for Salesforce links the work you do in your email to the records you need to update in the CRM.