BeeFree - BeeFree is an all-in-one solution that works anywhere you are.
MJML - The open source framework for responsive emails
Mail Designer 365 - Discover Mail Designer 365, the easiest way to design mobile-optimized HTML emails, templates and newsletter designs. Your HTML email designer for Mac.
EDM Designer - Make Responsive Email Templates. No Code.
Elite Email - Drag & drop email builder for awesome newsletters
SolidStudio Mosaico - Mosaico is a tiling window manager for Windows.