UPDATE 4/22/15 2:15PM EST - Microsoft has delisted the IP address. We are now routing mail through both IPs and everything is working as expected.
UPDATE 4/21/15 4:15PM EST - We have regenerated and queued all email that was refused by Microsoft blocks. Email is currently flowing; however we have still not received notification of a delist so we remain limited to mailing off one IP for now.
UPDATE 4/21/15 2:45PM EST - Microsoft has not yet delisted the new IP. We are now routing mail through only one IP until the issue is resolved.
As you know, we moved our mail servers to a new cloud provider, and as a result, our mail servers now have new IP addresses. (Refer to this article for more information.)
While this change did not affect any of the thousands of mail servers we relay mail to, Microsoft has a very short-sighted approach to receiving mail from new mail servers. Unlike all other mail providers (like gmail, yahoo, aol), Microsoft blocks mail from new mail servers by default.
So any of our clients who use Microsoft’s email service, may not be receiving emails from our email servers. This includes job board mailings and alerts, and HaleyMail newsletters and InstantMails, as well as all notifications, applications, form submissions from your HMG-hosted website, job board or HaleyMail accounts.
We have opened a ticket with our cloud provider to have them expedite this issue with Microsoft. At 10:20AM EST on 4/21/15, our cloud provider requested Microsoft delist our IP from being blocked.
Online, we have found hundreds of other companies that have had the same problem, but have had to wait for days for Microsoft to resolve this issue. Here is a link to an article on Microsoft’s Technet that highlights the issues other email providers are having with this policy.
To be clear, this is not an issue with our mail servers, but rather a most unfortunate policy that Microsoft has in place. Hopefully they will lift the block quickly and our clients will be able to receive email from our mail servers more reliably.