3:30 pm PST — Approximately 30 minutes ago, we detected flapping for one of the IP addresses used for the North American outbound smart hosts (for example, na0101.smtpout.com). We have updated DNS to point to an alternate IP address, which should resolve the immediate issue. Please note that the new IP address is on a different network than the original one: 208.70.91.x vs. 192.69.16.x. We plan on reverting the DNS changes to use the original 208.70.91.x address once we have determined the flapping behavior is no longer occurring.