What are some alternatives?
Nextcloud Mail - 💌 Mail app for Nextcloud
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
NeoMutt - NeoMutt is a command-line mail reader. It's a version of https://alternativeto.
Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
eM Client - eM Client is a Windows-based email client for sending and receiving emails, and managing calendars, contacts and tasks.