>>>>The whole schema sounds like the lazy montenegrin virus: "your machine is now, ahem, infected. Please format your system disk for us".
>>>
>>>Where do you press ctrl+u? I cannot read the source of this spam email.
>>
>>In my email client. The key combination didn't change, AFAIK, for the last 20+ years.
>
>I know I am using the wrong email client: Outlook.

To view email message headers in Outlook:
1. Open Outlook.
2. Double-click the message to open it in its own window.
3. Click the File tab and select Properties.
4. The properties for the selected message display in a dialog box. ...
5. Right click inside the Internet headers pane and click Select All. ...
6. Close the Properties box.

https://support.office.com/en-us/article/view-internet-message-headers-cd039382-dc6e-4264-ac74-c048563d212c