To be fair, Outlook.com has always been a bit shitty, if you're trying to deliver email to them. Last time it was reasonably good the service was still called Hotmail.

The problem is that we've allowed email to be centralized around a few massive providers, who do not care about customer service. If you're large enough, you probably have a contact at Microsoft for Outlook. Everyone else has to yell into the void and sometimes that works.