For many years we've been using CleanTalk blacklist API that helps fighting spam by checking IP addresses and email addresses. This API served us well, and filtered millions of spam messages over those years.
With CleanTalk Anti-Spam we get even better results then before! Almost no spam message reaches the inbox.
Further more, Anti-Spam also us to report a submission as spam and this way help them improve the system and block similar messages in the future.