On one server we have a frequent problem that SpamAssassin is not assigning scores to emails. The email headers look like this:

X-Spam-Status: No, score=
X-Spam-Score:
X-Spam-Bar:
X-Spam-Flag: NO

rather than have all the info in. In the past, restarting spamd seems to have helped, but now it doesn't do anything. Restarting Exim doesn't help either.

Any ideas please?