How to view full mail header on iPad?

You can't view full email headers in iOS Mail.

No kidding?

Wasn't the point of the OP to raise the issue that the "how" of getting to the headers needs to be addressed Instead of some pedestrian stating the obvious?

Just because the rank & file may not have a need does not mean that the ability to view, copy, paste, or forward headers intact is not of significant use for troubleshooting, debug, and legal purposes.

the closest thing i have found is to forward the message. When mail creates the new message, the email headers are at the top. It will show the reply-to, original email addresses, etc.

Can anyone tell me how to stop e-mail spam, without seeing ISP info in the header?

I've tried contacting/replying to the culprit (unfilteredpatriot.com) and also could not get my ISP to help.

I'd really prefer to stick with apple mail.

If it is important to you, AltaMail, which I use, has a Show Source method that displays the entire message as text, including all the headers.

Jim Hdk answered the question that was asked and the OP marked his answer helpful. We are not mind readers. If the OP wanted more info all he had to do was ask.