At my day job, we have a calendar integration that polls Microsoft's Graph API across hundreds of Microsoft 365 tenants. We saw our first metric spike in 5xx errors at 2026/11/12 17:33 UTC. As of writing it's 2026/11/13 09:44 UTC and we are still encountering a full outage, so 16 hours and 11 minutes.
With a SLA calculator [1], assuming no other downtime this month and entering 16h11m, we get:
* Yearly SLA: 99.82%
* Monthly SLA: 97.78%
Next, what is the actual agreement? I found an SLA document list here [2].
I downloaded Service Level Agreement for Microsoft Online Services (WW) English (2026/10/01). There's a heading for Exchange Online that says:
Uptime Percentage : Service Credit
< 99.9% : 25%
< 99% : 50%
< 95% : 100%
Which seems to agree with what the original commenter said for this month.
[2] https://www.microsoft.com/licensing/docs/view/Service-Level-...
These targets feel very very low nowadays.
99% uptime for email means 3.5 days/ year no email.
(although 99.9 = about 8 hours/year would seem bearable - but maybe not for a company like microsoft)