Initially, the performance from relatively untrained Bayesian filters may be less than that of other filtering techniques due to a lack of reference data, but once a useful number of good and bad emails have been processed through the filter and any required corrections carried out, the Bayesian filter can provide over 99% accuracy in spam filtering as has been demonstrated by the likes of Paul Graham.

As spammers find new ways to circumvent the filters that we use it's important that we stay ahead of them by ensuring our efforts to avoid and block their communications are adaptable. The Bayesian approach is simple, cost effective, auto-adaptive, can be very effective and is just the sort of thing that spammer's nightmares are made of!