Mailspring Alternatives

Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!

Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.

The #1 email warming service to improve your deliverability by generating realistic and meaningful engagement to your emails. Easy-to-use solution to help you land in the main inbox instead of the spam folder.

Visit website paid $19.5 / Monthly (Pro)

eM Client is a fully-featured email client for Windows and macOS with a clean and easy-to-use interface. eM Client also offers features for calendars, tasks, contacts, notes, and chat.

freemium

Mailbird is the best email client for Windows 7, 8 and 10

Airmail is a lightweight and lightning fast mail client for Mac.

Geary is an email application built for GNOME 3.

The Power Email App for busy professionals, like you.

The Bat! is a secure desktop email client for Windows, designed to protect your correspondence against third-parties and to save your time.

Mutt is a small but very powerful text-based mail client for Unix operating systems.

Apps/Evolution - GNOME Wiki!

Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues

Open Source

Claws Mail is an email client (and news reader), based on GTK+, featuring Quick response

K-9 is an opensource email client making it easy to chew through large volumes of email.