Gmail desktop app for macOS, Windows & Linux (formerly Gmail Desktop)
Monorepo hosting the proton web clients
Fast, secure email client with chat and kanban views
SaltOS, ERP, CRM, Business Management Suite, Josep Sanz Campderrós
Chat Messenger. E-Mail-Client. Websearch. Filetransfer.
Jnestor is another majordomo in java
Free and open source webmail software
Aspose.Email allows you to work with IMAP, POP and Exchange emails