Three years ago I investigated the effectiveness of some realtime black lists (RBL) [1]. I didn't find it worth implementing. I also looked into the result of

Three years ago I investigated the effectiveness of some realtime black lists (RBL) [1]. I didn't find it worth implementing. I also looked into the result of SPF [2] and again, found it not worth implementing. I rechecked the results for SPF earlier this year [3] and the results were the same. [1] http://boston.conman.org/2015/05/11.1 http://boston.conman.org/2015/05/11.1 [2] http://boston.conman.org/2015/04/12.1 http://boston.conman.org/2015/04/12.1 [3] http://boston.conman.org/2018/01/10.1 http://boston.conman.org/2018/01/10.1