BeeFree.io - Bee is MailUp's drag-&-drop editor for responsive design emails.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Topol.io - Create professional Email templates easily - Drag & Drop Email Builder.
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
MJML - The open source framework for responsive emails
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.