Email Sync Problems

How to Revoke ActiveSync Mail Client Access for Microsoft Accounts

Steven Parker Oct 13, 2026 868 views

Question details

The user needs to know how to force an ActiveSync mail client to stop synchronizing emails after updating Microsoft account security settings.

How to Revoke Access from ActiveSync Mail Clients

Product: ActiveSync / Microsoft Account
Device & OS: not provided
Scenario: Switching to passwordless authentication or signing out of applications, requiring the termination of an existing mail client session.
Observed behavior: The ActiveSync mail app continues sending and receiving emails through an active session despite security credential changes.

Before you start

Ensure you have access to a web browser and can log in to your Microsoft account's security dashboard to manage active sessions and app passwords.

Solution 1Recommended

Revoke the App Password

Use this solution if you previously generated a specific app password for the ActiveSync mail client to bypass two-step verification.

ActiveSync is a stateless protocol, meaning clients may continue to synchronize using existing cached credentials until those credentials or tokens fully expire. Revoking the specific app password immediately cuts off this access.

Access Security Settings

Locate App Passwords

Click on 'Advanced security options' and scroll down to the 'App passwords' section.

Revoke Access

Find the password that was generated for your specific mail app, click the 'Revoke' button next to it, and confirm your action.

Access Terminated: Once revoked, the mail app will no longer be able to sync. You will need to generate a new app password if you wish to restore access later.

Solution 2

Change Your Microsoft Account Password

Changing your primary account password forces all connected ActiveSync sessions to request updated credentials.

Solution 3

Review Account Sign-in Activity

Monitor your account to ensure the ActiveSync client has stopped syncing and to identify any suspicious login attempts.

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Frequently Asked Questions

Why does my ActiveSync mail app still work after I change my authentication method?

The ActiveSync protocol is stateless. This means that email clients can continue to synchronize using their existing cached credentials or active tokens until those specific session credentials expire on the server side.

What is an app password in a Microsoft account?

An app password is a randomly generated, single-use password that grants non-browser applications (like older mail clients or ActiveSync apps) permission to access your Microsoft account, effectively bypassing two-step verification.

How do organizational administrators block ActiveSync access for a user?

Administrators can log into Microsoft Entra ID and the Exchange Admin Center to investigate active user sessions, block specific mobile devices, and force a revocation of all active authentication tokens for the affected user.

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