Todd Lahman's comment spam blocking plugin that blocks automated spam with zero false positives.
Upgrade to Simple Comments. 10% Off with Coupon Code WPSFW.
Simple Comments can resolve many issues that Spam Free WordPress cannot. Simple Comments also has commercial grade spambot and hackbot protection. Experimenting with free plugins can be time consuming, but Simple Comments is available when you realize you need powerful spam protection.
There is no support for this free plugin, but there is support for Simple Comments.