I paid for Hotmail.
I paid for Opera (back in the day).
I paid for WinZIP.
I pay for any service I deem good.
When Hotmail went to Outlook, I stopped paying and threw it away. GMail was the answer, combined with my own server to manage email. Email actually comes to my GMail and my personal account at the same time. Downtime in the last 10 years? Zero, except scheduled reboots for kernel upgrades.
Yet, my workplaces (one of which was entirely Google Apps, another on-site Exchange AND Google) get downtime all the time. Literally, today, Google Drive threw a wobbly for a long time.
Cloud providers are third-parties. There's nothing wrong with remote servers. There's nothing wrong with hosting multiple servers in disparate geographic locations. There's nothing wrong with having virtualised servers or containers running on other's hardware.
But RELYING on them to always be up - as in this instance - is a nonsense. Deploy Outlook in-house AND in the cloud. And then at very least you can send / receive internal email and use your backup mail servers to send/receive email if you need to.
But putting your eggs into the hands of Microsoft, Google, Amazon or any other single entity to which you represent 0.00000000001% of their annual income is a stupid idea.
Oh, and for four years you couldn't log into Hotmail with a standards-compliant browser (Opera) when it was in its prime of development and had full support for all relevant standards. And the downtime on Hotmail once hit 20 days in one year. And I've seen Google downtimes in the days-per-year category too.
With those kinds of numbers, you're an idiot to rely on cloud alone without your backup MX / database replica being held in-house too. Because, you know what, my last workplace got 99.99% uptime. And we weren't even trying.