Tom Gerken
Tech reporter

I’ve been writing about outages for years, and one problem we always come up against is a question of scale.

Perhaps unsurprisingly, companies are rarely eager to tell us just how many people are affected when their products become inaccessible.

So, we often rely on the website Downdetector, which tracks online outages. It said it received 43,000 reports of issues with Microsoft Outlook at around 07:00 GMT, but that number is typically a low estimate.

For one thing, it’s only helpful for the countries where folk are awake - at its peak, there were more than 130,000 reports in the US, a number far lower now it's the middle of the night.

And the other glaring issue is it only really tells us how many people use the website. Think of this - are you affected by the outage and did you tell Downdetector about it?

I think for a lot of people, the answer to that question would be a “yes” followed by a “no”.

With 430 million people using Office365 services according to Microsoft, you have to wonder just how many aren’t able to access their emails this morning.

It all points to this being a massive, global outage.