Today I’m writing to provide some background about a change in how conditional access policies will soon be enforced when users access Office.com. Notifications about this change have been sent out, but several of you have asked for additional details.
On August 24th, a change will roll out that requires users to satisfy any policies set on Exchange Online and SharePoint Online when accessing Office.com. For example, if a policy requiring multi-factor authentication (MFA) or a compliant device has been applied to SharePoint or Exchange, this policy will also apply to users signing into Office.com.
Read more about it in the Enterprise Mobility & Security blog.