Notmuch is a very thin front end on top of xapian. Much like sup-mail, it focuses upon indexing your email messages.
Notmuch is written in C and an order of magnitude faster than sup-mail. Notmuch can be terminated during the indexing process, on the next run it will continue where it left off. Also like sup-mail, it does not provide a way to permanently delete unwanted email messages. It doesn't fetch or send mails, nor does it store your email addresses, you'll need to use programs like offlineimap, msmtp and abook for those tasks.
First time Usage
The program prompts you for the location of your maildir
The program prompts you for your primary and secondary email addresses
Running it as an email client
Notmuch is available from AUR:
The default frontend for notmuch is Emacs. It is developed by the same people that develop notmuch.
There's a vim interface available and included in notmuch. To start it, type:
vim -c NotMuch
alot is a standalone CLI interface for notmuch, written in python. It is available from AUR:
Alot uses mailcap for handling different kinds of files. This currently includes html mails, which means that you need to configure a ~/.mailcap file in order to view html mails. As minimum, put this line into your ~/.mailcap:
text/html; w3m -dump %s; nametemplate=%s.html; copiousoutput
More file handlers can be configured of course.
ner - notmuch email reader  is yet another CLI interface, apparently written in C++.