Home page: http://www.mew.org/
Installation: The github version is available via MELPA and the latest stable release is available via MELPA Stable.
Please read INSTALL.md
If you want to use Mew cloned from this repository, put the followings to your ".emacs".
(setq mew-icon-directory (expand-file-name"SHOMEWHERE/mew/etc"))
(add-to-list'image-load-path (expand-file-name"SHOMEWHERE/mew/etc"))