Our monitoring systems have been reporting normal operational status for the last 90 minutes. During the period in which the monitoring systems detected a potential issue, many messages were processed normally, but some messages sent through the Los Angeles and/or Dallas data centers were delayed.
From the investigation done thus far, we believe the most likely culprit was a third party technology used in the service for zero-hour spam and virus filtering, which was responding much more slowly than normal to queries.
Our engineers are continuing to monitor the systems and to investigate any other potential causes.
We apologize for the delays that some customers may have experienced.