Exchange Connection Problems

Fix Exchange ActiveSync Incorrect Password Error in Microsoft 365

Amos Gikunda Oct 22, 2026 869 views

Question details

A mobile email application using Exchange ActiveSync repeatedly reports an incorrect password even when the password entered is valid.

Fix Exchange ActiveSync Incorrect Password Error in Microsoft 365

Product: Microsoft 365 Exchange Online
Device & OS: not provided
Scenario: Connecting a mobile email application to Microsoft 365 using Exchange ActiveSync protocols.
Observed behavior: The connection fails with an incorrect password error because Basic Authentication has been disabled in Exchange Online in favor of Modern Authentication.

Before you start

Verify that your password is correct by logging into the Microsoft 365 web portal, and ensure you have global administrator access if you need to modify authentication settings.

Solution 1Recommended

Migrate to a Modern Authentication Email Client

The recommended and most secure solution is to transition the affected application or device to Modern Authentication, as Basic Authentication is permanently deprecated.

Microsoft replaces Basic Authentication with Modern Authentication to provide much stronger identity security. Older email clients that only rely on a username and password will fail to connect.

You must switch to an email client or application version that natively supports OAuth 2.0 (Modern Authentication) for Microsoft 365.

Check app compatibility

Verify if your current mobile email application supports Modern Authentication. If there is an update available, install it.

Re-add the email account

Remove the existing Exchange ActiveSync account from your device, and add it back using the 'Microsoft Exchange' or 'Office 365' option to trigger the modern web-based login prompt.

Switch to a supported app

If your native mail app does not support Modern Authentication, download and configure a fully supported client, such as the official Microsoft Outlook mobile app.

Migrate to a Modern Authentication Email Client

Enhanced Security: Using Modern Authentication enables multi-factor authentication (MFA) and conditional access, keeping your organizational data secure.

Solution 2

Temporarily Re-enable Basic Authentication via Admin Center

If you need immediate access while preparing for migration, a Microsoft 365 global administrator can temporarily re-enable the required protocol.

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Frequently Asked Questions

Why does Exchange ActiveSync reject my correct password?

Exchange Online disables Basic Authentication by default to prevent security vulnerabilities. When this happens, older mail clients using only a username and password get rejected, prompting an 'incorrect password' error despite the password being right.

What is Modern Authentication?

Modern Authentication is an identity management approach that relies on OAuth 2.0 tokens instead of storing and sending your actual password. It enables enhanced security features like Multi-Factor Authentication (MFA).

Can I permanently re-enable Basic Authentication?

No. Microsoft is permanently deprecating Basic Authentication in Exchange Online. Even if you use the admin diagnostic tool to temporarily re-enable it, Microsoft will eventually turn it off completely.

Which mobile email apps support Modern Authentication?

Most up-to-date modern email applications support it natively. This includes the Microsoft Outlook app for iOS and Android, Apple Mail on iOS 11 and later, and the latest versions of the Gmail application.

Outlook & Email Problems