If you have an Office 365 email account or a Google Apps at York email account you can directly report the headers of the phishing / spam message as per instructions located at Information Security website about reporting phishing:
Alternatively, you can follow the steps below for the appropriate mail client to view the full headers of an email:
- Google Apps at York: See Trace an email with its full headers.
- Microsoft Outlook for Windows: Double-click the message to open it in a new window. Select the File tab, and then, at the bottom, click Properties. The data is next to Internet headers.
- Mail (Microsoft Store App): The Windows 10 Mail client is lightweight and not fully featured. Viewing email headers in Mail is not possible at this time.
- Mail (macOS): With the message selected, from the menu, select Message, and then select either All Headers or Long Headers.
- Outlook Web App (OWA): Double-click the message to open it. Click the options icon (three dots near the top right), and then click View Message Details.
- Outlook for macOS: In your Inbox (or other folder), right-click or click the message, and then select View Source.
- Thunderbird (Windows, macOS): Click View, select Headers, and then choose All.
Once you have obtained the full mail headers, you can copy and paste that information in an email and send it to email@example.com.