Mailpile vs Mu4e

Uncluttered, highly intuitive, easy to use user interface.

Mailpile offers support for OpenPGP and S/MIME encryption and signatures in an easy to use manner.

The underlying architecture of Mailpile allows for themes that not only change the visual aesthetic of the client, but layout as well allowing for different UX designs.

Encryption is turned on by default.

The whole webmail client can be carried around on your external device (such as a USB stick) and used without having admin access to install.

Licensed under AGPL.

The search engine is at the very center of Mailpile. It was specifically designed to be able to handle large amount of e-mails without grinding the machine to a halt.

Additionally, the search includes a tagging feature that can automatically organize new mail by set rules or bayesian classifiers.

Mailpile is available in over 40 languages.

The UI is designed to allow for quick keystrokes to get around and is pretty clean.

Header View:

http://www.djcbsoftware.nl/code/mu/mu4e-2.png

Message View:

http://www.djcbsoftware.nl/code/mu/mu4e-3.png

Heavy actions never block emacs, unlike most other emacs email clients.

Mu4e has no folders or other organizational tools, rather it relies on very fast search queries to help you find your mail.

Using the (beta) org mode, Mu4e can compose fully rich text emails.

Doesn't require you to import address books for autocomplete, learns from your emails just like Gmail.