GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
MJML - The open source framework for responsive emails
Campaign Genius - Send dynamic email content through any platform, instantly.
BeeFree - BeeFree is an all-in-one solution that works anywhere you are.
MailChimp Snap - Send simple, photo-based email campaigns from your phone.
Elite Email - Drag & drop email builder for awesome newsletters