This.

I wonder if it is a generation gap thing. The young folks these days have probably used only Gmail, Proton or one of these big email services that abstract away all the technical details of sending and receiving emails. Without some visibility into the technical details of how emails are composed and sent they might not have ever known that the email headers are not some definite source of truth but totally user defined and can be set to anything.

98% of email users of any generation don't have the first clue how the protocol works.

Eh, nice times, when you could type an email just by telnetting to port 25...