The spam messages didn't have those headers. I went through my Junk Email Repository folder, now at over a 180,000 records since I last killed it, and found almost all of the messages didn't have Postini headers. Hmm... they weren't going through Postini, so Postini couldn't filter them.

I had read the Postini Admin guide when we first got the service. But the thing is 526 pages long and apparently I missed something important. In Chapter 23, IP Ranges and Security, on page 363, the manual recommends setting up your mail server to only accept email messages originating from Postini's servers. After all, the only email we get should come from Postini. That's a pretty important detail considered it makes Postini actually viable -- it's a shame they waited until page 363 to tell us about it.

In any case, that's what I did. I told the mail server to only accept messages coming in from our own internal machines or from Postini's IP addresses -- and reject everything else.

Ever since I did that, I've been a much, much happier boy. I've dropped from more than 7,000 messages a day to just about 700 -- and most of those are legitimate correspondence, press releases, and other things I need to know. 700 messages a day is still a lot, but not having to sift through thousands of questionable items has saved me almost six hours just this week alone.

It's been a really good week.

By the way, if you want to use Postini, give the Prominic guys a call. They provide the facilities for our network and are, hands down, the best ISP I've ever used.