If you happen to face an error while trying to deliver emails from your domain (@domain.com) to Outlook / Hotmail servers and you keep getting a bounce back error message like the following one :
550 SC-001 (BAY004-MC1F45) Unfortunately, messages from (x.x.x.x) weren't sent.
Please contact your Internet service provider since part of their network is on our block list.
It means a few things are going wrong with your sending domain.
Here are a few steps to solve this issue :
1. You want to assure you have your SPF records set-up. If you do not have these, please read our other article on how to set-up SPF records.
2. Microsoft mainly blocks any email that does not have their Reverse DNS set-up properly. It is not only a recommended step for email sending, but mainly a more than needed DNS record to have set-up. Follow our article on setting up your reverse DNS.
3. If you are still getting a denial after Step 1 and 2, you will be required to contact Microsoft to unblock your IP address. Unblocking your IP with Microsoft.
Note : Your server IP can be found within your VPS control panel.
1. Test your emails ! Use an awesome 3rd party tool to test and see how well your emails scores on spam. Check out Mail-Tester web application. It's easy to use and accurate.
2. Register with Microsoft Smart Data Network to better understand and improve your reputation with Microsoft email filtering.