From, Return-Path, Message-ID, Received: what headers reveal and how to read them.
The headers that matter
From: the visible sender. Must align with the authenticated domain (DMARC).Return-Path: where bounces go (envelope sender); basis for SPF alignment.Message-ID: the message's unique identifier.Received: the chain of servers traversed, bottom to top.Authentication-Results: the receiver's SPF/DKIM/DMARC verdict.
How to read them
Start from the bottom Received lines to reconstruct the path. Check that From and the DKIM/SPF domain match. The "Header" tab of the report above shows every header of the message you sent us.
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