Why Outlook 2013 Fails to Connect with Microsoft 365 Email

Microsoft 365 business email accounts are designed to use secure and modern authentication methods. However, many users still working on Outlook 2013 face a continuous password prompt error even though the same account works perfectly in the latest Outlook versions.

The reason behind this issue lies in the major security transition enforced by Microsoft.

? Root Cause

In 2022–2023, Microsoft globally disabled Basic Authentication — the old login method that only required a username and password. Outlook 2013 was originally built to use this old method.

Microsoft 365 now requires Modern Authentication (OAuth 2.0) which includes:
✔ Multi-Factor Authentication (MFA)
✔ Token-based secure login
✔ Better encryption

Since Outlook 2013 does not support this method by default, it fails to authenticate and keeps asking for the password.

✔️ Solution 1 — Upgrade Outlook 2013 to Support Modern Authentication

Outlook 2013 must be updated to at least:

Version: 15.0.4753.1001 (March 2015 Update) or later

You can check version in Outlook:
File → Office Account → About Outlook

After updating, Modern Auth must be manually enabled using Windows Registry edits:

Add the following registry entries:

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.0\Common\Identity]
"EnableADAL"=dword:00000001
"Version"=dword:00000001

[HKEY_CURRENT_USER\Software\Microsoft\Exchange]
"AlwaysUseMSOAuthForAutoDiscover"=dword:00000001

Restart the computer → Remove old profile → Add account again.
You should now see a Microsoft Sign-in Popup with company branding, not the old style password box.

✔️ Solution 2 — Use an App Password (Only if Basic Auth Still Enabled)

If your business uses MFA and Basic Auth is not fully shut down, you can create an App Password:

1. Visit: https://aka.ms/MFASetup

2. Generate “App Password”

3. Use it in Outlook instead of your normal password

⚠️ This is only a temporary workaround.

⚠️ Limitations & Future Risks

Even after fixes:

• Outlook 2013 is out of support

• Security patches are no longer provided

• Microsoft may permanently block older apps anytime

• Features like Conditional Access, SSO, and MFA** may fail

⭐ Best Recommendation

To avoid disruption and security risks:
➡ Upgrade to Microsoft 365 Apps, Outlook 2016, 2019, or New Outlook

New Outlook offers:
✔ Full Modern Authentication
✔ Better performance and cloud security
✔ Latest features & compatibility

? Final Thoughts

If you are facing password issues with Microsoft 365 on Outlook 2013, it’s not a user mistake — it’s a security-driven requirement from Microsoft. You can apply the fixes temporarily, but long-term reliability requires an upgrade.

If needed, professional assistance can ensure a smooth migration without data loss.

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