> information asymmetry where the spam artists don't know what signals you are looking for (which rules out open source). Machine learning mitigates this somew

> information asymmetry where the spam artists don't know what signals you are looking for (which rules out open source). Machine learning mitigates this somewhat - doesn't really matter if the code's open source if even the people who wrote it have no idea what's actually happening in the black box. Of course, that method of anti-spam has an entirely separate set of problems. But we've got those either way.