A pasted authentication header is not proof of the solo ad

Answer An Authentication-Results header is written by the system that received the mail, not by the solo ad seller. RFC 8601 defines that field. A pasted copy from an unknown forward is not that receiver's record. Ask for a header from a mailbox you can trace before you treat a pass as proof.

The note that started this: RFC 8601, Message Header Field for Indicating Message Authentication Status, RFC 8601.

By the end of the first week you have the from-name, the envelope, and the signature. Sellers answer those questions with a screenshot that includes a line saying pass. The line looks official because it uses the vocabulary of the specification. The vocabulary is only meaningful if you know who wrote the line.

RFC 8601 is the message header field for indicating message authentication status. A receiving agent inserts Authentication-Results after it checks SPF, DKIM, and the related methods it cares about. The field names the server that did the checking. It is a note from the receiver to the rest of the receiver's own system, and to anyone later who trusts that receiver. It is not a certificate the sender prints. A sender who pastes one into a sales page has copied a note that belonged to some other hop.

What is an Authentication-Results header?

It is a header a receiving system adds to record the authentication checks it performed. RFC 8601 defines that field. The sender does not get to invent it on the way out.

The practical reading is short. Look for the authserv-id, the name of the system that added the field. Then read the methods. A dkim=pass names a domain. An spf=pass names the domain that was checked against the envelope. Those passes are about that one delivery, to that one system, at that one time. They are not a reputation score, and they are not a promise about the next send to a different mailbox.

On a solo ad, the buyer is not the receiving system. You see what the seller chooses to show. If you buy solo ads from a page of cropped headers, you are reading a highlight. Cropped highlights omit the host name, the aligning identity, and the fail that sat two lines earlier. Ask for the whole header, from the first received line to the last.

• The host that wrote Authentication-Results is visible.
• The pass or fail is attached to a method and a domain.
• The message was sent to an address the buyer can open.
• A crop, a forward, and a retype do not count as that header.

Why is a forwarded paste weak proof of a solo ad?

A forward can be edited, and an Authentication-Results line from a mailbox you do not know was not written for you. The useful copy is a header from a mailbox you control, or from the seller's own logs.

Forwarding adds another Received line and can add another Authentication-Results line from the forwarder's system. The new line describes the forward, not the original broadcast. A seller who forwards a seed message to you has created a second transaction. The pass on the second transaction can look clean while the broadcast to the list was a different signature, a different from-name, or a different day.

There is a worse version. The text can be edited in a document and pasted under the screenshot. Nothing in the specification stops a person from typing the word pass. The specification only tells a real receiver how to record a real check. Your defense is boring. Have them mail a seed to an address you open yourself, and read the header in that mailbox. If they will not, you do not have a check. You have a paragraph.

What should a buyer ask for instead of a loose screenshot?

Ask for the full header of a message sent to an address you own, and ask which host added the Authentication-Results line. If they cannot produce that, the pass they are selling is a story.

Put the seed address in the quote. One copy to you, the same day, the same from-name, the same signer. You are not auditing the whole list. You are checking that the object they described is the object they transmit. A seller who can do this without drama is easier to trust than a seller who offers a collage.

Keep the result next to the refund line. Solo ad pricing that treats a pasted pass as delivery is a price for a story. The header is evidence only when you know who wrote it. On a quiet Friday, that is the whole ask.