- :returns: :class:`Message` or `None` if no message is found or if an
- out-of-memory situation occurs.
+ :returns: :class:`Message` or `None` if no message is found or
+ if any xapian exception or out-of-memory situation
+ occurs. Do note that Xapian Exceptions include
+ "Database modified" situations, e.g. when the
+ notmuch database has been modified by
+ another program in the meantime. A return value of
+ `None` is therefore no guarantee that the message
+ does not exist.