This was suggested by Srinivasa and is intended to make it easier to
integrate notmuch into an mbox-loving mail client.
notmuch library
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+Add an interface to accept a "key" and a byte stream, rather than a
+filename.
+
Provide a sane syntax for date ranges. First, we don't want to require
both endpoints to be specified. For example it would be nice to be
able to say things like "since:2009-01-1" or "until:2009-01-1" and