08-20-2016, 08:24 PM
This is a known and irritating issue. You have a Microsoft-based email address and, for no apparent reason, Microsoft has blocked communications originating from my server's IP address due to user reports or past spam activity, apparently. I've already submitted a request to have it removed but haven't heard back yet. Until then, all email originating from any of our sties destined for Microsoft email addresses (@hotmail.com, @outlook.com, @msn.com, @live.com, etc.) is being rejected.