Hi Sebastian;

Sorry this sat so long in the queue.

I agree it doesn't cost much to add it, but offhand I'm not sure what
the use case is. It would be be good to (briefly) mention this in the
commit message and also expand the docstring for the variable a bit,
since this is currently our only documentation.

> +(defcustom notmuch-query-prefix nil
> +  "Add a prefix to the standard query."
> +  :type 'string
> +  :group 'notmuch-search)
> +

In addition to general comments about, I'd say that "standard query" is
a bit ambigious for me. It sounds like it would be added e.g. to
saved-searches.  Maybe "default" search, with some discussion of where
it is used (so people don't have to read the source to figure it out).

d