eml517 B

EML — Reply With References and No In-Reply-To

The same reply expressed the other way round: a References chain with no In-Reply-To. Together with its twin it isolates which of the two headers a threading implementation actually reads, since either alone is sufficient under RFC 5322.

Email parsing Conversion testing

Preview — first 13 lineseml

From: Sam Rivera <sam@meridiansupply.example>
To: Maya Chen <maya@brightside.example>
Subject: Re: Standing order for Q1 (SAMPLE)
Date: Sun, 15 Feb 2026 09:00:00 -0800
Message-ID: <p7-thread-refs@meridiansupply.example>
References: <p7-thread-root@brightside.example>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

Reply body. What matters here is which threading headers are present
and what they point at; the text is the same across the set on purpose.

Specifications

Wave: p7
Seed: 20260807
References: <p7-thread-root@brightside.example>
In Reply To: absent
Depth: 1
Line Endings: CRLF (RFC 5322)

Testing contract

Expected to pass

Scenario: Attach a reply to its parent when References is the only ancestry header present.
Expected result: The message threads under <p7-thread-root@brightside.example>, matching the placement of its In-Reply-To-only twin exactly.

What is a .eml file?

An EML file is a single email message stored in the RFC 822 / MIME format — plain-text headers (From, To, Subject, Date, Message-ID) followed by the body, which may be plain text, HTML, or a multipart structure with alternative bodies and file attachments encoded in base64.

How to use this file

Use an example EML to test email header parsing, MIME decoding, HTML-part handling, attachment extraction, and EML-to-other-format conversion.

How to use this file for testing

“EML — Reply With References and No In-Reply-To” is a deterministic Novus Examples fixture for Email parsing, Conversion testing. Standards-compliant RFC 822 messages — plain, multipart text+HTML, and with an attachment — plus an MBOX mailbox, for testing header parsing, MIME decoding, attachment extraction, and mailbox splitting.

Documented properties for this file: seed 20260807 · CRLF (RFC 5322). Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.

Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.

Email fixtures use fixed dates, message IDs, and MIME boundaries so runs are reproducible, and every address is fictional. Test header parsing, MIME decoding, attachment extraction, and EML/MBOX conversion against the documented structure.

Code examples

from email import policy
from email.parser import BytesParser

msg = BytesParser(policy=policy.default).parse(open("p7-references-only.eml", "rb"))
print(msg["subject"], msg["from"])