Microsoft Outlook for the web: Third-party cookie block causes users to sign in again on Chrome and Edge

Users of Microsoft Outlook for the web may face the inconvenience of having to sign in again due to third-party cookie blocks in Chrome and Edge, following a migration to MSAL. This issue affects users without device Single Sign-On (SSO), who have third-party cookie blocking enabled. SSO-enabled Windows devices will not be affected as they will sign in without requiring further interaction. The rollout of this change will start from late September 2024 and end by late December 2024. Outlook for the web is undergoing an authentication platform migration to a public client authentication model using MSAL, which Google's third-party cookie block may affect. To overcome this, Outlook for the web will present a banner prompting users to refresh their session, which will enable navigation to Entra ID to refresh their token. This issue only affects Outlook for the web users and users of other applications such as new Outlook for Windows, Outlook (classic), Outlook for Mac, Outlook Mobile for iOS and Outlook Mobile for Android are not affected.

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