[spc476]

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

[2] http://boston.conman.org/2015/04/12.1

[3] http://boston.conman.org/2018/01/10.1