Paste raw message headers to get the delivery path with per-hop delays, SPF, DKIM and DMARC verdicts, the Exchange Online spam verdict and sender mismatch flags. Everything runs in your browser; nothing is uploaded or stored.
In Outlook: open the message, File, Properties, copy everything from Internet headers. In OWA: open the message, the three-dot menu, View, View message details.
Oldest hop first (origin at the top). Delay is the wait between one hop and the next; amber over 1 minute, red over 5 minutes.