EMail messages appear as plain text files

So events for received email messages are going into Zeitgeist, they do show up in the Activity Journal. But they show up as text files, which isn't user-friendly.

I wrote the code inserting the events, so it's possible that I did something wrong and I would greatly appreciate pointing out any flaws.

So the event insertation is this snippet:

            var log = new Zeitgeist.Log ();
            var event = new Zeitgeist.Event.full (Zeitgeist.ZG_RECEIVE_EVENT,
                Zeitgeist.ZG_SYSTEM_NOTIFICATION, "app://postler.desktop",
                new Zeitgeist.Subject.full (message.uri,
                Zeitgeist.NMO_EMAIL, Zeitgeist.NMO_MAILBOX_DATA_OBJECT,
                "text/plain", GLib.File.new_for_uri (message.uri).get_parent ().get_uri (),
                message.sender, ""));
            log.insert_events_no_reply (event);

The file here is a full email message in raw form.