Taken from MS O365 Health Portal:

Title: Can't access email User Impact: Users may be unable to connect to the Exchange Online service. More info: Other services with dependencies on Exchange Online, such as calendar access through Microsoft Teams, could also be intermittently unavailable. Current status: We're continuing to repair the communication issue between mailbox-hosting infrastructure and components that facilitate access and other users actions. In parallel, we're exploring additional potential mitigation actions to more quickly restore service. Scope of impact: This issue could potentially affect any of your users if they are routed through the affected infrastructure. Start time: Friday, July 19, 2019, at 9:30 AM UTC Root cause: A potential communication issue between service components that host the affected mailboxes and infrastructure that facilitates user connections is affecting access to Exchange Online. Next update by: Friday, July 19, 2019, at 5:30 PM UTC

On Sat, Jul 20, 2019 at 12:38 AM Ross Tajvar <ross@tajvar.io> wrote:

....What's the issue?

On Fri, Jul 19, 2019 at 12:35 PM Nathanael Catangay Cariaga <ncariaga@gmail.com> wrote:
This might be an off topic since this is a confirmed issue with Microsoft but I'm just wondering how vast are the affected users on this issue.

west coast user here.

-nathan