search engines

Hi,

I would like to know about your experiences with the search engines.
I’ve used notmuch, but unfortunately the substring queries only work for
the beginning of a word. Then I tried mairix, but now I see, that it
only works with ASCII (that was not clear from the man-page).

So before trying swish-e, swish++, namazu and mu, I would like to know,
how these engines work for you.

Perhaps we could make a survey and a feature table?

I try to start such a table:

engine   substrings       regex   UTF-8   encrypted messages
--------------------------------------------------------------
notmuch  start of word    no      yes     yes
mairix   yes              no      no      no

TIA for your help,
-- 
           Peter