YouniqMail
Local-only, privacy and customizable modern email client
YouniqMail is a modern email client which only communicates between your computer and the mail server. The YouniqMail developers don't even have any servers. It saves all you mail data only local on your computer. The mail client is highly customizable with a lot of features and systems to let you organize your emails and inboxes. You can adapt it to your work/-mailflow.
