[tjohns]

It's been some time since I ran my own mail server, but from what I recall, some spam filters actually give more negative weight (i.e. message is more likely to be spam) to a SOFTFAIL (~all) than a FAIL (-all), even though this contrary to the spec.

Spamassassin's rationale was that many of the tutorials online never explained the difference, so the majority of mailservers were just using SOFTFAIL everywhere. More paradoxically, messages that had a hard FAIL result were statistically more likely to be due to a misconfiguration, based on an empirical analysis.

Like I said though, it's been quite a while since I've had to deal with this. I'm not sure if it's still true or not.