try this: View>Headers>all

The reason those headers don't appear in the body of received messages is because the same information is displayed in the Header Pane, the section above the body. It is possible to display additional headers in the Header Pane, without showing All headers, but I don't know of an easy way to also show them in the body.

Your method is probably best if you only need to copy the message with the RWH headers, and if you save the reply as a draft, then select Edit As New Message on the draft, you could send it to yourself, or another recipient.

Thanks all. I will just continue to click reply or forward, which populates the headers in the body, then copy them.

Copy them to what ? Do you need to just have a file that contains basic headers and content?

Here are some other options.

For example You could save email as eml file. Another person can then open it using Thunderbird.

You could right click on email and select 'Print' - that gives you the option to print both basic headers and email content as a hard copy. But it also gives you the option to use 'prt scr' key and select the area required and save as an image file.

If you install 'ImportExportTools NG' then you can right click on email in Message List and select 'Export Messages as > PDF format OR using same addon extension - select 'Export Messages as > Plain Text Format > Message Only - that will save as a simple text file showing basic headers or full headers depending upon settings.