SpamSieve suddenly sending EVEYTHING to spam folder

Spam Sieve had been working very well, with very few false positives or negatives. Then yesterday my email/web provider had a system outage, and today SS is sending absolutely everything to the spam folder. I have not changed or upgraded SS or anything else on my system. What could be causing it, and what can I do?

Thanks for any help you can provide.

SpamSieve 2.9.19
Apple Mail 4.6
Mac OS X 10.6.8

This is probably due to a setup problem in your mail program. Please see the Why is every message going to the Spam mailbox? page.

Hmmm, if SS was working correctly and I haven’t changed anything, why would it be the setup?

Because the setup could change without you doing anything, e.g. due to iCloud or a problem with your hard disk.

That was it, thanks a lot. SS appears to be working correctly again.