Apparently eSafe eats PDFs from redhat.com, as they are obviously SAPM. Our IT guy in head office, says that eSafe is the best thing since sliced bread (which I don't actually like), and that we only get 1% false-positives, compared with the industry average of 5%.
I've no idea what the industry averages are, but I've had one false positive ever at home with spamassassin, and I get a better identification rate too. It's not that I've done anything fancy yet, I'm running a stock Debian Sarge, with spamassassin and simple procmail filtering.
I have no idea how good eSafe really is, but it seems to let through a lot of obvious spam, and eats useful content. My system at home is clearly better, and given that I get more email at home than work, and my home email address has been out on the net for longer, it's just not wishful thinking.