READING EMAIL HEADERS
Almost every question about why an email did or did not arrive is answered in its headers, and almost nobody knows how to read them.
This is the short version: which headers matter, what the authentication results tell you, and how to trace a message backwards.
What this covers
Chapter 1 of 5
Where each client hides them.
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Chapter 2 of 5
Reading a path backwards, hop by hop.
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Chapter 3 of 5
What the receiving server concluded about SPF, DKIM and DMARC.
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Chapter 4 of 5
Two different addresses, and which one is checked.
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Chapter 5 of 5
What does not add up in a spoofed message.
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Check yours
Everything above, checked on your domain in about ten seconds. Free, no account.