Mu4e

Starting with version 0.9.8, mu provides an emacs-based e-mail client which uses mu as its back-end: mu4e.

Afterlogic Webmail

Webmail is an open-source webmail script for existing IMAP servers.

Alpine is a fast, easy to use email client that is suitable for both the inexperienced email user…

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

Apps/Evolution - GNOME Wiki!

Geary is an email application built for GNOME 3.

Kontact is the integrated Personal Information Manager of KDE.

Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.

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

Add forums and commenting to your site. Unlimited posts, users and traffic, for free. Embeddable, styleable and scriptable.

NeoMutt is a command-line mail reader. It’s a version of https://alternativeto.

í ½í² Mail app for Nextcloud

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

The Power Email App for busy professionals, like you.

RainLoop is a web based email client.

Web-based IMAP email client

SOGo is groupware server with a focus on scalability and open standards.

SquirrelMail is a standards-based webmail package written in PHP.

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

Get your encrypted mailbox for free.

eM Client is a Windows-based email client for sending and receiving emails, and managing calendars, contacts and tasks.