Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
aerc - Highly efficient and extensible email client for the terminal
Geary - Geary is an email application built for GNOME 3.
Netlify - Build, deploy and host your static site or app with a drag and drop interface and automatic delpoys from GitHub or Bitbucket
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.
Mu4e - Starting with version 0.9.8, mu provides an emacs-based e-mail client which uses mu as its back-end: mu4e.