Right now — today, June 3, 2026 — Microsoft is dealing with an unresolved Exchange Online outage (incident EX1331830). Email is delayed or failing for Microsoft 365 customers across North America, Europe, and Asia-Pacific. Microsoft has acknowledged it and is investigating. There is no fix time yet.
If your business runs on Outlook, this is your problem too.
This Isn’t a One-Off
June 1 alone saw three separate Microsoft 365 incidents: an Office Web files outage in Teams, a Copilot outage lasting over four hours, and an MFA setup failure. Now Exchange is down. Within a week, we’ve had four major M365 disruptions.
Cloud email is reliable — until it isn’t. And when it goes down, the cost is measured in lost deals, missed client messages, and operations grinding to a halt.
What You Lose When Email Goes Dark
- Inbound leads — They’re going somewhere else. Or nowhere.
- Client trust — A missed response is a slow business killer.
- Internal coordination — Most “quick questions” happen over email. Now they’re not happening at all.
- Authentication fragility — When Microsoft’s auth systems wobble, your single sign-on wobbles with them.
What You Should Do Today
If your team is currently stuck:
- Switch to a backup channel — Microsoft Teams (if it works), phone, or a personal email route for urgent client communication.
- Document the outage — Note timestamps, affected services, and business impact. Microsoft will need this for SLA credits, and you’ll need it for your own post-mortem.
- Don’t trust MFA prompts right now — Attackers love outages. The FBI just warned about Kali365, a phishing-as-a-service kit specifically designed to bypass Microsoft 365 MFA. Outage windows are prime time for credential theft.
- Tell your customers — A short “we’re experiencing email delays” note on your website or social channel buys you goodwill.
What You Should Do This Week
Outages are inevitable. Getting wrecked by them isn’t.
- Set up email continuity — A secondary mail routing path (even a simple Google Workspace fallback) keeps critical messages moving.
- Audit your M365 dependencies — If Exchange going down takes your whole business offline, your risk surface is too narrow.
- Enable number-matching MFA — Defeats most Kali365-style bypass attempts.
- Run a tabletop drill — Pick a date, simulate an email outage, see what breaks.
Don’t Wait for the Next Outage to Build a Plan
Every business running on Microsoft 365 needs a documented “email is down” runbook. Not a vibe. Not a Slack thread. A real procedure your team can follow at 9am on a Tuesday when Outlook stops loading.
At NSI Tech, we build M365 environments with continuity baked in — redundant identity, fallback mail routing, and the kind of monitoring that tells you about an outage before your users do.
If your Microsoft 365 setup hasn’t been pressure-tested lately, today is a good day to fix that.