⚠️ Some browsers like Firefox, Brave, or Safari have cookie-blocking features that prevent Microsoft's seamless authentication from working.
This results in an authentication error when opening an e-mail.
This is reflected in the logs by an error such as: 13001
How to get around this authentication problem?
Several workarounds are available, depending on the browser
On some browsers, they can be done manually by the user or via Intune / GPO by an administrator.
Firefox
Via Intune / GPO by an administrator
Enable single sign-on (SSO) on Windows: https://support.mozilla.org/en-US/kb/windows-sso
This operation can also be deployed via Intune or GPO.
Intune:
Create a registry key for users (GPO) HKCU\Software\Policies\Mozilla\Firefox with a REG_DWORD value named WindowsSSO and for data 1.
Example below:
By the end user
Users can deactivate enhanced anti-tracking protection on https://outlook.office.com/mail/ .
Safari
Users must disable cross-site tracking. To do so, uncheck Prevent cross-site tracking in Settings → Privacy.
Brave
By end user
The user must authorize all cookies in the advanced controls of active shields
