There was a partial outage today that affected the Akismet API.
Starting around 21:53 UTC a network issue caused approximately 10% of API calls to fail. Our systems team routed traffic to alternate servers and the network problem was fixed. The partial outage lasted 20 minutes.
The WordPress Akismet plugin will automatically re-try any comments that were not correctly filtered as a result of the problem.
The API is now back to normal and responding to all traffic.