What are some alternatives?
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
KanbanMail - A Kanban board for your emails.
eM Client - eM Client is a Windows-based email client for sending and receiving emails, and managing calendars, contacts and tasks.
Drag Pro - Transform Gmail into organized To Do lists (like Trello)
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
Flow-e - Turn your Gmail or Office365 inbox to a Visual Task Board.