2:30pm Pacific / 10:30pm GMT — Investigation has shown that the issues today may have been the result of several very large-scale spam runs.  Inbound message processing has improved at the California data center since this morning but has still experienced intermittent slowness.  Message processing has been operating normally at other facilities for the last several hours.  The operations team is still working to assess and mitigate the issue, and we will continue to post updates here as more information becomes available.