What are some alternatives?
Nextcloud Mail - 💌 Mail app for Nextcloud
Mutt - Add forums and commenting to your site. Unlimited posts, users and traffic, for free. Embeddable, styleable and scriptable.
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.
Alpine - Alpine is a fast, easy to use email client that is suitable for both the inexperienced email user...
Apple Mail - There’s big news attached.