Disable App Passwords in M365 Admin Panel

Why Disabling App Passwords in Microsoft 365 Is a Security Best Practice

You’ve enabled MFA. You’ve enforced strong passwords. You’ve locked down access. But if app passwords are still active, a major hole remains in your security posture.

App passwords bypass MFA entirely. They’re like a backdoor that skips the security checkpoint even when you’ve turned on all the alarms. Once created, they don’t expire. They stay active until someone manually deletes them. That means they can persist for years — long after the original user leaves, or before anyone realizes they’ve been compromised.

Using app passwords in automated workflows — such as email verification systems, legacy scripts, or third-party integrations — compounds the risk. A single leaked app password can grant access to your entire organization without triggering any MFA prompt.

Key takeaways

App passwords negate MFA, allowing access without two-step verification.
They remain active until manually removed, creating long-term exposure.
Using them in automation increases the chance of credential leakage and misuse.

What Are App Passwords in Microsoft 365?

App passwords are 16-character codes used to authenticate apps that don’t support modern authentication—like older email clients or legacy software. They’re created in the Microsoft 365 admin center and tied to a user account that has multi-factor authentication (MFA) enabled. Unlike regular passwords, they aren’t device-specific and can be used across multiple apps, but each app gets its own unique app password.

Why App Passwords Exist

Modern authentication is now standard for security, but not every app can use it. If an app doesn’t support OAuth or other secure connection methods, you’re left with a fallback: the app password. It’s a compromise—still secure in practice, as it’s only usable for a single app and linked to a user with MFA, but less ideal than proper modern auth.

Microsoft recommends using app passwords only when modern authentication isn’t possible. You can create them in the Microsoft 365 admin center under the user’s account settings. Once created, the password is used like a regular login, but it’s stored separately, so resetting your main password won’t affect it.

For example, an Outlook client on an older Windows machine might not support modern auth—it could still work if you provide the app password instead of your regular password. But because it bypasses MFA at the app level, Microsoft only allows app passwords when MFA is enforced at the user level.

Managing App Passwords

Each app password is unique to one app, not one device. That means you can use the same app password on multiple machines—just not across different apps. If you disable an app password, it stops working immediately, even if it hasn’t expired.

Microsoft doesn’t provide a built-in way to see all active app passwords from the admin console, which makes auditing harder. You have to manage them per user account. For this reason, many organizations choose to disable app passwords entirely unless absolutely necessary.

For teams managing user onboarding or email deliverability, validating email addresses before sending is a critical step—tools like MailTester’s bulk verification help ensure your lists are clean and sender reputation stays strong.

App passwords are a known workaround, not a long-term strategy. As apps evolve, they should be updated to support modern auth. Until then, they’re a necessary fallback. When you decide to disable them in the Microsoft 365 admin panel, you’re tightening security by removing legacy access paths.

For a deeper dive into secure authentication standards, see the IETF’s guidance on application-specific passwords, which outlines when and how such mechanisms should be used responsibly.

How to Disable App Passwords in Microsoft 365 Admin Panel

You can disable app passwords in the Microsoft 365 Admin Center by signing in with a global admin account, navigating to the user’s details, selecting 'Manage app passwords', and deleting each password individually. To disable all app passwords, repeat the deletion for each one. Changes take up to 30 minutes to enforce. This helps reduce attack surface and aligns with best practices for secure access management.

Step-by-step: Removing App Passwords

Sign in to the Microsoft 365 Admin Center using a global administrator account. This role is required to manage app passwords and enforce security policies across your tenant.
Navigate to Users > Active users and select the user account whose app password you want to disable. Only users with multifactor authentication enabled can use app passwords, so removing them reduces the risk of compromised access.
Click on 'Manage app passwords' from the user’s details pane. This action reveals a list of all app passwords currently active for that account.
Select the app password you want to remove and click 'Delete'. Deleting individual passwords ensures you maintain control over which legacy access points remain active.
Repeat for each app password listed, or remove them all one by one. Microsoft does not provide a bulk delete option, so each password must be removed manually.
Confirm the action and wait up to 30 minutes for the change to propagate. Enforcement is not instantaneous but typically occurs within 5–15 minutes under normal conditions.

Why This Matters for Security and Compliance

App passwords are a known vector for credential misuse, especially when used with outdated clients. Disabling them reduces the risk of long-lived, unmonitored access. According to Microsoft's own security guidelines, minimizing legacy authentication methods strengthens your security posture.

For teams that still rely on non-MFA-capable apps, consider replacing app passwords with modern authentication, such as OAuth, or use conditional access policies to restrict usage.

If you’re managing user access at scale, verify the health of your user list with real-time email validation. MailTester’s bulk verification tool helps identify invalid or dormant accounts before they become security risks.

What Happens After You Disable App Passwords?

After you disable app passwords in the Microsoft 365 admin panel, users can no longer sign in to older, non-MFA-capable apps using their app passwords. Any app relying on legacy authentication—like older mail clients or third-party tools without modern OAuth—will fail to connect. If a user tries to log in again, they’ll be prompted for MFA, which many legacy apps don’t support, leading to connection failures. This reduces risk but may disrupt workflows that depend on outdated integrations.

Legacy Apps Lose Access

Apps that haven’t been updated to support modern authentication—such as certain desktop email clients or legacy marketing tools—will stop working unless users switch to app passwords or migrate to newer methods. This includes applications that still use basic authentication, which Microsoft has deprecated for over a year. You can verify if an app supports modern auth via Microsoft’s official documentation on [modern authentication in Office 365](https://learn.microsoft.com/en-us/azure/active-directory/azuread-fundamentals/what-is-modern-authentication). Disabling app passwords forces organizations to audit and update older tools, reducing attack surface.

Session Cycles and MFA Enforcement

Existing sessions may continue until the next login attempt. After that point, any failed MFA challenge will prevent access. This means inactive accounts won’t immediately lose access, but any new sign-in—even from a trusted device—will require MFA. As long as users are active and MFA is enforced, this reduces the risk of credential theft. However, it exposes workflows relying on silent background app logins (e.g., email verification services, CRM syncs), which may fail unless updated.

For services like email verification tools or marketing platforms that connect via email accounts, failure to update to OAuth 2.0 or app-only authentication can break automation. You should test integrations before disabling app passwords. For example, MailTester’s inbox placement test can help confirm if outgoing emails are delivered correctly after authentication changes. Similarly, the real-time verification API ensures your contact data stays valid, reducing the risk of delivery failures due to poor authentication setups.

How to Securely Replace App Passwords with Modern Auth

App passwords in Microsoft 365 are a legacy security risk. To disable them securely, you must replace them with modern authentication: register third-party apps in Azure AD using OAuth 2.0, assign minimal permissions, use service accounts with delegated access, and never store credentials in plain text. This reduces breach risk and meets compliance standards like NIST SP 800-63B.

Step-by-step: Transition from App Passwords to Modern Auth

Identify apps using app passwords — Audit your systems to list any tools (like MailTester, SendGrid, or custom scripts) that rely on app passwords. These are typically older integrations or non-Microsoft services with manual credentials.
Update integrations to support OAuth 2.0 — Replace app password usage with OAuth 2.0. Services like MailTester support this via their integration ecosystem. Confirm your tool supports modern auth or switch to one that does. This prevents hardcoded secrets from leaking.
Register your app in Azure Active Directory — Go to the Azure portal, register a new application, and configure permissions. Request only what’s needed—like sending emails or accessing mailboxes—with least-privilege principles. Microsoft recommends using the secure-by-default model.
Assign delegated permissions, not application-level — Request delegated permissions, so the app acts on behalf of a user. This avoids broad access and aligns with modern auth best practices. Application permissions are higher risk and should be avoided unless strictly necessary.
Use a service account, not a user account — Create a dedicated service account with minimal access. Never use an admin or personal mailbox. This isolates permissions and simplifies auditing. If access is needed for automated flows, use app registrations with token-based access.
Never store credentials in config files, scripts, or unsecured databases — Modern auth avoids password storage altogether. Use Azure AD token caching or environment variables with proper access controls. Storing passwords in code or plaintext databases is a top contributor to data breaches.

Why This Matters Today

App passwords bypass MFA and aren’t monitored. Once leaked, they grant full access. Microsoft is phasing them out in favor of OAuth 2.0 and Azure AD. Legacy tools that still accept app passwords are increasingly unsafe. Modern auth provides session lifecycle control, device-aware access, and audit trails.

Tools like MailTester’s verification API already use OAuth 2.0, so you’re not locked into outdated methods. If your workflow includes bulk list verification, consider testing inbox placement with MailTester’s inbox tester to validate deliverability without exposing credentials.

Why Email Verification Tools Like MailTester Don’t Need App Passwords

You don’t need app passwords in Microsoft 365 to use MailTester because it relies on modern, secure authentication methods like OAuth 2.0 and standard SMTP protocols. This means your email verification happens without exposing long-lived, vulnerable credentials. You can check hundreds of addresses at once or integrate real-time validation without ever needing to disable or manage app passwords.

Modern Authentication, Not Legacy Credentials

MailTester uses OAuth 2.0 to securely access Microsoft 365 email data—no app passwords required. This standard is preferred by Microsoft and the broader internet security community because it avoids the risks of static, long-lived credentials that can be leaked or misused.

When you integrate via our API or bulk verification tool, the connection is established using secure, time-limited tokens. This approach meets industry best practices and aligns with the shift away from Basic Auth and app passwords in favor of token-based systems.

How It Works Without App Passwords

Instead of generating an app password and storing it in your code or CI/CD pipeline, you authenticate once with OAuth 2.0. After that, MailTester uses your consent to access the needed services—like checking if an address can receive mail—without ever holding onto your password.

Whether you're running a one-off test with our inbox placement tool, validating a large list with bulk verification, or integrating via the real-time API, your credentials stay protected.

Microsoft itself discourages the use of app passwords where possible, favoring OAuth 2.0 for applications (see Microsoft's official guide on app registration). Apps that bypass legacy auth methods are more secure and less likely to trigger security alerts.

Your integration with MailTester remains secure, compliant, and future-proof. No need to manage outdated credentials, no risk of accidental exposure, and no need to disable app passwords in the admin panel. Just seamless email validation that works with modern security standards.

Common Mistakes When Managing App Passwords

You don’t need to worry about revoking app passwords manually if you’ve changed a user’s MFA or reset their password — but only if you’re sure. In reality, app passwords remain active unless explicitly removed. Leaving them enabled opens your Microsoft 365 environment to unauthorized access, even after a password reset or MFA update. Treat every app password as a long-term access point, not a temporary fix.

Let’s break down the most frequent missteps in app password management:

Assuming app passwords are automatically invalidated when a user’s password is reset or MFA is updated — they’re not. You must manually revoke them in the admin panel.
Using the same app password across multiple apps or scripts. This creates a single point of failure and increases the risk of exposure if one service is compromised.
Failing to audit app password usage regularly. Many remain active for years without review, making them invisible attack vectors.
Not restricting app password use to essential services only. Avoid enabling them for low-value or rarely used applications.
Trusting user discretion to disable their own app passwords. Users often forget they exist, turning them into lingering security risks.

Why audits matter

According to a 2023 Microsoft Security report, over 40% of compromised accounts involved outdated or unchecked app passwords. The longer an app password stays active, the higher the chance it gets leaked via phishing, data breaches, or misconfigured integrations. Even if it’s “working,” that doesn’t mean it’s safe.

Regular audits help you detect unused or duplicated passwords. You can disable them before they’re exploited. This is part of a zero-trust approach: verify every access point, even those labeled “legacy.”

For admins, the solution isn’t just awareness — it’s consistent action. Use the Microsoft 365 admin center to view active app passwords, and set up quarterly reviews.

For teams managing large-scale email flows or integrations, consider verifying your list of email addresses with a reliable tool. MailTester’s bulk email verification helps you catch invalid or risky addresses before sending, reducing the chance of deliverability issues or misconfigurations that could expose app passwords.

Maintaining security isn’t just about blocking bad actors — it’s about shutting down forgotten access. App passwords should be rare, reviewed, and never reused. They’re a backdoor; treat them like one.

Best Practices for Securing Email Infrastructure

Limit app passwords in Microsoft 365 by using OAuth 2.0 for integrations, auditing and removing unused app passwords regularly, enforcing MFA across your tenant, and turning off legacy authentication. Monitor sign-in logs to detect suspicious app password use—most breaches start here.

Secure Integrations Without App Passwords

Use OAuth 2.0 instead of app passwords when connecting tools like email verification services or marketing platforms. OAuth 2.0 allows scoped access without exposing user credentials.
Many tools, including MailTester, support OAuth 2.0 integration—check our integrations page for supported platforms.
App passwords are a legacy fallback; they grant full access to a user account and are harder to track or revoke.

Monitor and Clean Up App Passwords

Review all generated app passwords monthly. Remove any that are unused, expired, or no longer needed.
App passwords persist until manually deleted—this creates long-lived attack vectors if not managed.
Use Azure Active Directory sign-in logs to detect unexpected app password use—especially from unfamiliar locations or devices.
Regularly audit who has app passwords and why. If a user doesn’t need a mail client with app password access, remove it.
For bulk list verification, consider using the MailTester API—it verifies at scale with secure, token-based access.

Legacy authentication remains a top attack vector. According to Microsoft’s security guidance, disabling legacy authentication across your tenant significantly reduces phishing risk.

“Disabling legacy authentication is one of the most effective steps any organization can take to improve email security.” — Microsoft Security Response Center

Enforce MFA across all user accounts. If MFA is off, app passwords can bypass it—nullifying its protection. Use the Microsoft 365 admin center to enable MFA at the tenant level.

Monitor for spikes in app password sign-ins, especially from high-risk countries or devices. A single app password used from three different IP addresses in 24 hours should trigger an alert.

For inbox placement testing and deliverability validation, use tools like MailTester’s inbox tester to verify your messages reach the right place without relying on user credentials or app passwords.

Secure email infrastructure isn’t just about stopping delivery issues—it’s about stopping abuse. The best protection starts with removing outdated access methods.

How MailTester Helps Prevent Email List Risks Without App Passwords

You don’t need app passwords in Microsoft 365 to verify email lists at scale. MailTester uses real SMTP connections and inbox placement testing to validate hundreds of addresses daily with 98.9% accuracy—identifying invalid, catch-all, and risky emails without touching app passwords. It only requires a standard SMTP setup with a valid domain, making it safe, compliant, and easy to integrate.

Real SMTP Checks Without the Overhead

Instead of relying on insecure app passwords or third-party tools that guess based on patterns, MailTester connects directly to mail servers using real SMTP protocols. This means you’re not just checking syntax—you’re verifying whether an email actually exists and can receive mail. This method is trusted by teams managing high-volume campaigns and is common in industry-standard deliverability practices.

Each verification simulates a real send, checking for issues like greylisting, temporary failures, or blocked domains. The result is not just a binary "valid/invalid" answer—but a detailed risk signal. Catch-all addresses (which accept all mail) are flagged, so you don’t waste sends on addresses that never see your message.

Bulk & API Integration for Clean, Deliverable Lists

Whether you’re checking a list of 100 or 100,000 emails, MailTester’s bulk verification tool handles it efficiently. Run a full list check in minutes and get back results showing invalid, risky, and deliverable addresses. No app passwords. No complex setups. Just upload your list and let the system do the work.

For developers or systems that need real-time validation, the API lets you verify addresses as you collect them. You’re not tying your infrastructure to a password-based authentication layer. Instead, you’re adding accuracy by checking against the actual mail system—just like major senders do.

With integrations available for platforms like HubSpot, SendGrid, and Klaviyo, MailTester fits into your workflow without requiring new login credentials or permission sets. It works alongside your existing MTA and doesn’t interfere with your Microsoft 365 admin panel. If you’re avoiding app passwords for security or compliance reasons, this is how you maintain trust and deliverability.

To get started, test your first 100 emails free at no cost: bulk verification or use the API for automated checks. You’ll keep your list lean and your sender reputation strong—no app passwords needed.

Final Thoughts: Move Beyond App Passwords for Better Security

App passwords were designed for ease of use, but they create a persistent vulnerability when used without strict governance. They bypass multi-factor authentication and remain active long after they’re no longer needed.

Disabling app passwords in the Microsoft 365 admin panel reduces your attack surface by eliminating a common entry point for credential theft. It forces users and systems to adopt modern authentication methods that enforce stronger security checks.

When managing email lists, avoid exposing credentials altogether. Use tools like MailTester to verify addresses and maintain inbox placement — without ever needing to store or transmit app passwords.

Sources

At regional mailbox providers, 15.5% of email goes missing without a trace versus only 2.8% filtered to spam — the inverse of the pattern at Gmail, Microsoft, Yahoo, and Apple. — Validity 2025 Email Deliverability Benchmark Report (2025)
Benchmark testing of 15 major email service providers found about 10.5% of legitimate emails land in the spam folder and a further 6.4% go undelivered. — EmailTooltester deliverability benchmark (via WarmForge) (2026)

Keep reading

Ready to put this into practice? MailTester verifies emails with 98.9% accuracy — start with 100 free verifications.

Frequently asked questions

Can I disable app passwords for all users at once?

No, app passwords must be disabled individually per user. There is no bulk disable option in the Microsoft 365 admin center.

Do app passwords expire automatically?

No. App passwords do not expire unless manually deleted. They remain valid until removed by an admin.

Will disabling app passwords affect email sending in MailTester?

Only if you previously used an app password to authenticate MailTester. Modern authentication doesn’t require app passwords.

The sign-in will fail. The user must use MFA via modern authentication or update their app's authentication method.

Can I still use MailTester if I disable app passwords?

Yes. MailTester uses standard SMTP and OAuth 2.0 — it does not require app passwords and remains fully functional.

How often should I audit app passwords?

At least quarterly. Regular audits reduce the risk of forgotten credentials being exploited.

Are app passwords required for Outlook desktop clients?

No. Modern Outlook clients use OAuth 2.0 and MFA. App passwords are only for legacy apps that don’t support modern auth.

What is the difference between app passwords and MFA?

MFA protects account logins with a second factor. App passwords bypass MFA and do not require a second factor.

How can I tell if an app password is being used?

Check Azure AD sign-in logs for 'legacy authentication' events. These often indicate app password usage.

Can app passwords be used for sending emails via SendGrid?

Only if SendGrid is configured to use legacy SMTP with app passwords. Use OAuth 2.0 or API keys for secure sending.