Some of our customers have had e-mail to sites hosted by Outlook fail and get bounced with something on the order of cannot lookup sender address or some such.

     Microsoft claims troubles leaving there fine, i.e., they have no issue but Down Detector says otherwise and I’ve had reports from other sites experiencing the same, so just a heads up, this issue is affecting multiple sites to Outlook addresses or addresses hosted by outlook and the issue is not on our end.