Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
Yesware - Sell smarter with email tracking and more
Geary - Geary is an email application built for GNOME 3.
Mixmax - At Mixmax, our mission is to change how the world communicates. We’re an email productivity platform that helps sales, customer success, and recruiting teams do their jobs better.
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.
SalesLoft - The simpliest way to build the most accurate and targeted lists of leads on the internet