Configuring preferences and options in Outlook.com
Personal Outlook.com accounts do not provide a user-accessible audit log showing exactly when forwarding was enabled or disabled.
If you disabled an inbox rule without deleting it, open its details while keeping it disabled; the destination address may still be recorded there. Disabling a rule preserves it while stopping it from running. This can help document account access, but they are not a forwarding history and cannot establish who enabled forwarding or how long it operated.