Kontact - KMail Alternatives

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

Geary is an email application built for GNOME 3.

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)

Apps/Evolution - GNOME Wiki!

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

Mailspring is a mail client for Mac, Windows and Linux.

Open Source

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

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

Kube is a modern communication and collaboration client built to just work.

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

Sylpheed is a simple, lightweight but featureful, and easy-to-use e-mail client (mailer, MUA).

Balsa is an e-mail client for GNOME, highly configurable and incorporating all the features you...

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

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