> The MSP's policy can be whatever they want as long as it IS advertised.
No.
Suppose the MSP uses bayesian filtering? How would one go about advertising a policy that depends on bayesian filtering? You'd have to publish the contents of your filter table. The only people who could benefit from that would be spammers, who could use the data to customise their spam.
In general, telling the world what your filtering policies are is just going to cause spammers to try to sidestep your policies. The only policy that you maybe ought to publish would be along the lines of "We filter out spam; that sometimes results in false positives. Sorry."
No.
Suppose the MSP uses bayesian filtering? How would one go about advertising a policy that depends on bayesian filtering? You'd have to publish the contents of your filter table. The only people who could benefit from that would be spammers, who could use the data to customise their spam.
In general, telling the world what your filtering policies are is just going to cause spammers to try to sidestep your policies. The only policy that you maybe ought to publish would be along the lines of "We filter out spam; that sometimes results in false positives. Sorry."