Excerpts from sebastian's message of Mon Feb 01 14:29:44 -0600 2010:
> 2)
> > JSON output for "notmuch search/show" with ability to filter output fields
> > "search" --> "search --output=thread_id,date,number,author,subject,tags"
> >  "show"  --> "search
> > --output=message_id,tags,path,header,body,attachments"
> 
> YES PLEASE :-). notmuch seems designed to work in an ecosystem of
> surrounding scripts, feeding data in and out. But we are all currently
> limited to regexes for that. And heck, I hard a hard time understanding
> why all hell broke out until I found that i had added a tag containing
> parentheses which made my regex fail. :-). XML, JSON, any structured
> output would be nice.
> 
> And as for filtering: YES, PLEASE :-). notmuchsync and many other 3rd
> party apps would love that. As father of notmuchsync, I can tell you my
> little script hickups very badly when slurping in 200k mails (including
> text bodies) just to find out the maildir tags of those mails.
> 

There's been a JSON patch waiting for a month now.