[notmuch][] is a clean mail indexer.  You know you got an email from
someone with their current phone number, but can't remember where you
put it?  Notmuch to the rescue:

    $ notmuch show from:jdoe@example.com home phone
    message{ id:DF741236-…@example.com … filename:/home/you/mail/…

    header{
    John Doe <jdoe@example.com> (October 04) (inbox)
    Subject: new contact info
    From: John Doe <jdoe@example.com>
    To: You <you@big.edu>
    Date: Tue, 4 Oct 2011 18:08:57 -0600

    header}

    body{

    part{ ID: 1, Content-type: text/plain
    I've got a new home phone number:

      123-456-7890.

    Cheers,
    John

    part}

    body}

    message}

[[Gentoo]] installation is simple:

    $ emerge -av notmuch
    $ notmuch setup
    (interactive creation of ~/.notmuch-config)
    $ notmuch new
    (initial indexing)

When you want to update the index, just run `notmuch new` again.  You
can get fancy with [[offlineimap]] hooks:

    [Account Upsilon]
    postsynchook = notmuch new

but I just have a Bash alias in my [[dotfiles]] along the lines of

    alias offlineimap-in='offlineimap && rm -f ~/mail/Junk/* && notmuch new'

You can also get fancy with [mutt integration][mutt], but I just
`grep` the search results on the command line to get what I want.

P.S.  I'm cleaning out my backlog of half-completed blog posts today,
can you tell?

[notmuch]: http://notmuchmail.org/
[mutt]: http://git.upsilon.cc/cgi-bin/gitweb.cgi?p=utils/mutt-notmuch.git;a=summary

[[!tag tags/tools]]