Roundcube - Web-based IMAP email client
Gmail - Gmail is available across all your devices Android, iOS, and desktop devices. Sort, collaborate or call a friend without leaving your inbox.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
GMX - GMX Mail is a German-based free webmail service provided by GMX (Global Mail Exchange).
Rainloop - RainLoop is a web based email client.
Zoho Mail - Zoho Mail is a secure, encrypted, and enterprise-ready email solution, a suite of apps tailor-made for your organization's needs.