This means that some keys you might not expect will be returned. If there was a key in the database for Marc Edu <mit.foo.com>, this would be returned for by the above query. If you don't want to see all these extra matches, you can select ``Only return exact matches'', and only keys containing the specified search string will be returned.
This algorithm does not match partial words in any case. So, if you are used to specifying only part of a long name, this will no longer work.