Proton Mail Bridge application
Lightweight Open Source webmail written in PHP and JavaScript
Monorepo hosting the proton web clients
Simple, modern & fast web-based email client
Wrappers around msmtp for use as queueing MTA with extra features
cab
Business webmail modular application with mobile client
Simple Lotus Notes mail client
BNM helps you design and send massive emails in HTML format
Newsletters / emailing Tool
Microsoft Exchange compatible server and client libraries