Outlook online will log you out

Juan Troche 0 Reputation points
2026-11-09T00:55:47.02+00:00

O365 is a great platform, but trying to access Outlook is often frustrating, as the web application will actively log you out.

This never happens with any other O365 application, just Outlook.

Clearing all cookies sometimes fixes the issue, but not always.  Often times the only way to access Outlook online is through a private browser session.

It'd be great if a login session survived opening Outlook.

Outlook | Web | Outlook on the web for business | Sign in
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  1. Kai-Ex 2,565 Reputation points Microsoft External Staff Moderator
    2026-11-09T01:27:11.4966667+00:00

    Dear Juan Troche,

    Thank you for sharing your experience.

    I understand how frustrating this can be. Outlook on the web should normally maintain your sign-in session like other Microsoft 365 applications. Since clearing cookies or using a private/incognito browser sometimes resolves the issue, this may indicate a problem with browser cookies, cached authentication tokens, browser extensions, or sign-in policies configured by your organization.

    A few questions that may help narrow down the cause:

    • Does this happen in multiple browsers (for example, Edge, Chrome, and Firefox), or only one browser?
    • Is this a personal Microsoft account or a work/school Microsoft 365 account?
    • Does the sign-out occur immediately after opening Outlook on the web, or after a period of inactivity?
    • Are you seeing any specific error message when Outlook signs you out?
    • If this is a work or school account, has your organization configured Conditional Access policies, sign-in frequency policies, or security settings that may require more frequent reauthentication?
    • Do you have any browser extensions enabled that block cookies, tracking, or scripts?

    Moreover, here are some things I recommend you check:

    1/ Temporarily disable browser extensions, especially ad blockers, privacy tools, or security extensions that may interfere with Microsoft authentication (Click the ⋮ menu > Extensions > Manage Extensions).

    2/ Try a different supported browser, such as Microsoft Edge or Google Chrome, to determine whether the issue is browser-specific.

    3/ If you're using a work or school account, check with your Microsoft 365 administrator to see whether Conditional Access policies or Sign-in Frequency policies have been configured, as these can require users to reauthenticate more frequently. For references: How do I find my Microsoft 365 admin?, What is Conditional Access? and Conditional Access adaptive session lifetime policiesAs a temporary workaround, continuing to use an InPrivate/Incognito session can help determine whether the issue is related to browser data or extensions.

    Thank you for your patience and understanding. If you have any questions, please feel free to reach out. I'm looking forward to your update

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  2. AI answer

    2026-11-09T01:29:46.4133333+00:00

    Configure the normal browser profile to retain and permit Microsoft sign-in cookies, then disable privacy or content-blocking extensions for Outlook; private browsing working while the normal profile fails points to browser-profile handling rather than Outlook intentionally ending every session.

    Fix the normal browser profile

    Since clearing all cookies has only helped temporarily and private browsing already works, use these more targeted checks:

    1. Allow cookies for Outlook and Microsoft authentication
      • Ensure the browser is not blocking cookies or automatically deleting them when Outlook closes.
      • If third-party/cross-site cookies are blocked globally, add site exceptions for:
        • outlook.office.com
        • login.microsoftonline.com
        • microsoftonline.com
      • In Microsoft Edge, set Settings → Privacy, search, and services → Tracking prevention to Balanced for testing.
      Outlook uses cookies across its own and Microsoft authentication domains to preserve authentication state. For example, ESTSAUTH maintains the current browser session, while ESTSAUTHPERSISTENT supports remaining signed in after closing the browser.^1^
    2. Disable extensions selectively
      • Temporarily disable ad blockers, tracker blockers, script blockers, cookie managers, and security/privacy extensions.
      • Close all browser windows, reopen the browser, and test Outlook.
      • If that works, re-enable extensions individually to identify the conflicting one.
      Microsoft specifically notes that Outlook can have problems when AdBlock, UBlock, or pop-up blockers are enabled.^2^
    3. Test a new browser profile
      • Create a new profile in the same browser rather than another private window.
      • Sign in with only the affected Microsoft 365 account and open Outlook.
      • If the session survives, migrate bookmarks to the new profile instead of repeatedly clearing the old profile’s cookies.
    4. Use a current supported browser
      • Test the latest Edge, Chrome, or Firefox on Windows; on macOS, use current Edge, Chrome, Firefox, or Safari 16 or later.^2^

    Distinguish a browser problem from an organization policy

    A tenant idle-session policy is more likely when Outlook works normally at first and later displays “Your session is about to expire” after inactivity. That policy applies per browser session and can sign the user out of all Microsoft 365 tabs in that browser.^3^

    For a work or school account, ask the Microsoft 365 administrator to check:

    1. Microsoft 365 admin center → Settings → Org settings
    2. Open Security & Privacy → Idle session timeout.
    3. Review whether it is enabled and the configured duration.
    4. Modify or disable it only if that matches the organization’s security requirements.

    This setting is tenant-wide and cannot be scoped directly to individual users or groups. Microsoft Entra Conditional Access is required when different session behavior is needed for selected users or device conditions.^3^

    The older Outlook-specific activity-based authentication timeout began retirement in January 2024, so administrators should prefer the Microsoft 365 idle-session setting for current configuration.^4^

    If a new browser profile with permitted cookies and no extensions still signs out immediately—and no tenant timeout prompt appears—the next step is Microsoft 365 support, because the remaining issue may involve the account or tenant session rather than local browser state.

    References

    1. Cookies used in Microsoft 365 web apps and services
    2. Supported browsers for Outlook on the web and Outlook.com
    3. Idle session timeout for Microsoft 365
    4. Activity-based authentication timeout for Outlook on the web in Office 365
    AI-generated content may be incorrect. Read our transparency notes for more information.

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