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!
eM Client - eM Client is a Windows-based email client for sending and receiving emails, and managing calendars, contacts and tasks.
NeoMutt - NeoMutt is a command-line mail reader. It's a version of https://alternativeto.
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
Postbox - The Power Email App for busy professionals, like you.