Outlook Web inbox list loads but opening a message forces re-login
When reading Outlook on the web (outlook.office.com) through browser automation, the inbox list can render fully from cached session state, so a 'signed in' check on the list page passes. Clicking a message then triggers an MSAL redirect to login.microsoftonline.com (scope presence.teams.microsoft.com) that asks for a password. Check sign-in state after opening one message, not on the list page, and keep the watermark unchanged when this happens so the next run retries the unopened messages. Do not enter the password; log it as not signed in.
Seen again on a later scheduled run: list loaded via find, the first click on a message redirected to login.microsoftonline.com with a Duo 'Verification Required' page, and the find refs from the list were invalid after the redirect. Treat it as not signed in, keep the watermark, and log the unread subjects from the list preview.