1. Check Your Internet Connection
Ensure you have a stable, high-speed internet connection:
- Try loading other websites.
- Switch to a different network (like mobile hotspot) temporarily to test.
Poor connectivity can cause authentication to fail at the server level.
2. Clear Cached Credentials
Incorrect saved login info can block Outlook:
- Open Control Panel → Credential Manager → Windows Credentials.
- Find anything related to Outlook or MicrosoftOffice.
- Remove them and re-enter your account details when prompted.
Fresh credentials usually fix authentication loops.
3. Repair Office Applications
Damaged Office files can interfere with server communication:
- Go to Control Panel → Programs → Programs and Features.
- Select Microsoft Office → Change → choose Quick Repair (or Online Repair for deeper fixes).
4. Temporarily Disable Antivirus/Firewall
Some security programs block Microsoft services unintentionally:
- Turn off the antivirus/firewall temporarily and check Outlook again.
- If Outlook connects successfully, adjust firewall settings to allow Office apps.
Be sure to turn your security software back on afterward.
5. Update Outlook and Windows
Running outdated versions might trigger server rejection:
- Open Outlook → File → Office Account → Update Options → Update Now.
- Install all pending Windows Updates.
Updates ensure that your authentication protocols match Microsoft's latest security standards.
6. Create a New Outlook Profile
A corrupt profile can prevent proper server communication:
- Open Control Panel → Mail → Show Profiles.
- Click Add to create a new profile.
- Reconfigure your email account in the new profile and test.