When trying to send an e-mail to any outlook.com address i get this in return:
Unfortunately, messages from [135.181.6.248] weren’t sent. Please
contact your Internet service provider since part of their network is on
our block list (S3150). You can also refer your provider to Troubleshooting
Microsoft replies that they are not blocking our IP’s. We have replied that that is not the case as we are still unable to get our mails through. The team is still in discussions with MS on resolving this. Will update if there is any progress.