Newton Mail

vs

FastMail

K-9 Mail is an open source email client focused on making it easy to chew through large volumes of email. K-9 Mail is designed for both novice and power users and offers lots of features for everyone. It provides features like Push IMAP Support, GPG & PGP/MIME support, Per Account Notifications, Unified Inbox, White and Dark Theme, and Signatures.

Tutanota is the world's most secure email service, easy to use and private by design. Tutanota brings secure email for everybody.

MyMail is your app for any email: convenient interface, flexible notification settings, and high speed.

Arguably the most popular email service in the world, Gmail provides a email inbox for over 1.5 billion users. With Gmail you can create an email account for free that manages emails and contacts in the same application. Gmail is web-base but provides clients for mobile devices and supports third-party programs that synchronize email content through POP or IMAP protocols.

A free an open-source email client developed openly by the Mozilla Foundation and the community. Thunderbird is easy to setup and customize and supports POP and IMAP. The email client comes with all features needed to search, filter, write and manage emails, but also have builtin support for live chat between contact and RSS/Atom feed reader.

World's largest secure email service providing end-to-end encrypted email accounts. ProtonMail is based in Geneva, Switzerland and protected by Swiss privacy laws. The software is openly developed with fully open source code.