What are some alternatives?
Nextcloud Mail - 💌 Mail app for Nextcloud
Mu4e - Starting with version 0.9.8, mu provides an emacs-based e-mail client which uses mu as its back-end: mu4e.
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Mutt - Add forums and commenting to your site. Unlimited posts, users and traffic, for free. Embeddable, styleable and scriptable.
NeoMutt - NeoMutt is a command-line mail reader. It's a version of https://alternativeto.
Claws Mail - Claws Mail is an email client (and news reader), based on GTK+, featuring Quick response