The Mu4e Reference Manual: an E-mail Client for Emacs

mu4e (mu-for-emacs) is an e-mail client for GNU-Emacs version 24, built on top of the mu1 e-mail search engine. mu4e is optimized for fast handling of large amounts of e-mail.
Some of mu4e?s highlights:

• Fully search-based: there are no folders, only queries.
• Fully documented, with example configurations
• User-interface optimized for speed, with quick key strokes for common actions
• Support for non-English languages (so ?angstrom? will match ?Angstrm?)
• Asynchronous: heavy actions don?t block emacs3
• Support for crypto
• Address auto-completion based on the contacts in your messages
• Extendable with your own snippets of elisp