When comparing Mu4e vs gnus, the Slant community recommends Mu4e for most people. In the question“What are the best native e-mail clients for Linux?” Mu4e is ranked 8th while gnus is ranked 11th. The most important reason people chose Mu4e is:
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)
Ranked in these QuestionsQuestion Ranking
Pro Can write rich text emails
Using the (beta) org mode, Mu4e can compose fully rich text emails.
Pro Built-in Autocomplete
Doesn't require you to import address books for autocomplete, learns from your emails just like Gmail.
Heavy actions never block emacs, unlike most other emacs email clients.
Pro Fully Search Based
Mu4e has no folders or other organizational tools, rather it relies on very fast search queries to help you find your mail.
Pro It supports IMAP and POP3
… but you can use DavMail to connect to Exchange server via EWS.
Pro Everything is customizable
Yep, really. From Outlook-mode, where Outlook-typical TOFU mails are “repaired”, up to a high-sophisticated scoring and SPAM filtering, footer lines with quotes, rules depending on the recipient, MIME formatting, boxquotes, etc.
Con Difficult documentation
Originally a newsgroup reader, so its documentation uses Usenet terminology for everything -- which is confusing.