I would check out the outpostfirewall.com forums there are a couple of issues reported with spam terrier. This is the first release after beta so it may have some way to go yet.
I have to say I don’t like it, I don’t want it integrated in my email client, I also prefer MailWasher that is independent of your email client and not limited to just two email clients. I have read a little in the Agnitum newsletter and visited the site page and I have to say I’m still in the dark as to how it works. I believe you still have to download the spam emails and then filter it. On dial-up this is a huge waste of what limited bandwidth I have.
I have no idea if it will stay free or free to existing Agnitum customers or whether it will become a part of a suite, etc.
At the moment there is a proposed Outpost Security Suite Pro, which I’m personally against as suite bloatware. They are spending a lot of time on that suite when the outpost pro isn’t Vista compatible and unlikely to be until the 2nd half of the year. I think they have their priorities completely wrong, but at least the stand alone Outpost Firewall Pro is to continue. It is these muddled actions that also and I think trying to get a slice of every pie would also make me wonder about Spam Terriers future.