On Wed, May 4, 2011 at 4:26 PM, Felipe Contreras
<felipe.contreras@gmail.com> wrote:
> +output=$(notmuch search from:'search-by-from@' | notmuch_search_sanitize)

I don't think this does what you think it does.  Xapian only
understands double quotes around phrases, not single quotes.
Furthermore, a single quote after a prefix prevents that token from
acting as a prefix, so you search is finding messages containing the
*word* "from" and the phrase "search by from" *anywhere* (which is a
phrase not because of the quotes, but because of the hyphens).

The test results happen to be the same if you use single quotes or
double quotes, but for very different reasons.