11:30am Pacific — Per our prior posts, on Friday October 9, Microsoft resolved the deferral issues seen with deliveries to Office 365 from our Amsterdam datacenter. The Microsoft product engineering team resolved the issue by excluding our affected IP addresses from the rate limiting system within Exchange Online Protection which had recently changed; these changes at Microsoft impacted deliveries from us and from other email service providers as well, including McAfee / MX Logic.
Since that time, we have been in communication with Microsoft about preventing a recurrence of the issue. This morning, Microsoft confirmed that they have updated the rate limiting system within Exchange Online Protection, to exclude all of our active IP addresses at all of our datacenters. This was good news and should provide some confidence that the issue will not recur.
We appreciate the patience last week of all affected customers, as well as the collective efforts of the numerous people who likewise were in communication with Microsoft to push for a resolution of the issue.