The question is: What other use is there for this "guaranteed" spam I am getting? It's only about 40 messages a day but is it useful to anyone else, or should I just keep deleting it?
You could feed it to spamassassin -r instead of sa-learn --spam. But that only works for single messages, not whole mboxes.
spamssassin -r will report to spamcop (sa 3.0+), learn as spam, and if you have them installed report to dcc, razor and pyzor.
Reporting to common spam tracking systems like these, and perhaps the ftc's uce account, is about the only "other use" there might be for your spam.
