+ [maildir]
+ synchronize_flags = R:replied; D*:deleted; S:~unread;
+
+In the library interface this could be implemented with an array of
+structures to define the mapping (flag character, tag name,
+inverse-sense bit (~ above), and tag-when-any-file-flagged
+vs. tag-when-all-files-flagged (* above)).
+
+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
+have the other endpoint be implicit. Second we'd like to support
+relative specifications of time such as "since:'2 months ago'". To do
+any of this we're probably going to need to break down an write our
+own parser for the query string rather than using Xapian's QueryParser
+class.
+
+Make failure to read a file (such as a permissions problem) a warning
+rather than an error (should be similar to the existing warning for a
+non-mail file).