1. Double-check Microsoft Account Password & 2FA
- Make sure you are using the correct password.
- If you have Two-Factor Authentication (2FA) enabled:
- Generate an app-specific password at Microsoft Account Security and use it in Outlook.
2. Reset Your Windows Credentials
- Go to Control Panel → Credential Manager → Windows Credentials.
- Remove all entries related to Microsoft accounts like:
- MicrosoftAccount:user@live.com
- Outlook:YourEmail@outlook.com
- Restart Outlook and re-enter your login credentials when prompted.
3. Clear Mail App Data (Optional)
- Go to Settings → Apps → Mail → Advanced Options → Reset.
- This will clear the cache and force a fresh sync.
4. Adjust Network and DNS Settings
- Try switching to a known working network (e.g., mobile hotspot).
- Set public DNS:
- Preferred DNS server: 8.8.8.8
- Alternate DNS Server: 8.8.4.4
5. Disable Firewall/Antivirus Temporarily
- Security software may block Outlook from completing a secure handshake.
- Temporarily disable antivirus and firewall.
- If Outlook works afterward, add exceptions for Outlook and Office to your security software.
6. Enable "Allow Less Secure Apps" (if applicable)
- For legacy systems, go to Outlook.com → Account Security → Enable allowing less secure apps.
7. Try Signing in via Web Mail
- Open a browser and go to https://outlook.live.com or https://account.microsoft.com.
- Sign in with the same email credentials you’re using in Outlook or the Mail app.
- If you’re prompted to verify your identity or complete a security check, follow the steps.
- If the sign-in works on the web but not in the app, it confirms that the issue is client-side—such as outdated tokens, cached credentials, or local configuration problems.
- Once the account is working on the web, go back to Outlook, remove the account, and re-add it to refresh the sync.