Because I block some breathtakingly wide swaths of the net from sending mail to FP, I temp-fail almost everything (the exception is anything in the zen.spamhaus.org RBL; they’ve proven consistent enough that I permanent-fail anything on their list). This has served me really well, as the stripped-down spam-sending software on the exploited machines treats a temporary failure the same as a permanent failure, and I can unblock legitimate senders before they give up. Unfortunately, the 419-scammers have started finding mail hosts that retry on temp-failures, so I have had to hard-block three bad actors (that apparently are not such bad actors that they made it into zen) so far.
On the other hand, the recent flood of phishing has died down.