Outlook repeatedly shows a Windows Security / password prompt even though the password is correct. Mail may stop syncing.
1. Close Outlook. 2. Open Windows Credential Manager → Windows Credentials and remove every entry starting with MicrosoftOffice16_ or Outlook. 3. Sign out of Office: any Office app → File → Account → Sign out. 4. Reopen Outlook, sign in with your work email and approve the MFA prompt. 5. If the prompt returns, contact support — we will check the account's sign-in logs and the profile's authentication mode.