When Outlook suddenly stops sending and receiving mail while Outlook on the web works fine, the cause is almost always the desktop client’s cached authentication token — not your mailbox or the Microsoft 365 service itself.
Common Symptoms
- Outlook shows “Disconnected” or “Need Password” in the status bar
- Send/receive fails with an authentication error
- Outlook on the web (browser) works normally
- Problem appeared right after a password change or MFA re-enrollment
Possible Causes
- A cached, now-invalid authentication token in Windows Credential Manager
- Modern Authentication (OAuth) not fully re-establishing after a password change
- Outlook profile referencing an outdated Exchange server setting
- A conditional access policy blocking the specific device or app
Before You Begin
Confirm Outlook on the web works with the same account first — if it doesn’t, the problem is with the Microsoft 365 account itself, not the Outlook desktop client, and you should check Method 2 (sign-in) before anything else.
Method 1 — Check internet connectivity
Confirm general connectivity
Open a browser and load a few unrelated websites to rule out a broader network issue before assuming it’s Microsoft 365-specific.
Method 2 — Clear cached credentials
Method 3 — Repair the Outlook profile
Repair the account
Select the profile, click Properties → Email Accounts → select the account → Repair, then follow the prompts.
Method 4 — Run the Microsoft 365 repair tool
Open Apps & Features
Settings → Apps → Installed apps, find Microsoft 365/Office.
Run Quick Repair, then Online Repair if needed
Quick Repair fixes most issues in a few minutes; if it doesn’t help, run Online Repair (takes longer, redownloads components).
If multiple users report the same problem at the same time, check the Microsoft 365 Service Health dashboard before troubleshooting individual machines — it may be a service-wide incident.
Watch the Video
Prefer watching? This tutorial covers the same steps.
A step-by-step fix for Outlook desktop clients that stop syncing after a Microsoft 365 modern authentication change.
Watch on YouTube →Frequently Asked Questions
Why does Outlook on the web work but the desktop app doesn’t?
The web app authenticates fresh each session, while the desktop client relies on a cached token that can go stale — clearing that cache (Method 2) is usually the fix.
Will repairing Office delete my emails?
No — a Quick or Online Repair reinstalls application components, not your mailbox data, which lives on the Exchange Online server (or in a local .ost cache that stays intact).
Conclusion
Clearing cached credentials and repairing the Outlook profile resolves the majority of “disconnected” errors — reserve conditional access policy review for cases with an explicit AADSTS error code.
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