eml1.3 KB

EML — DSN Returning Only the Original Headers

The same bounce as its twin, except the returned content is text/rfc822-headers — the privacy-preserving form most large providers send. A processor keyed on message/rfc822 finds nothing here and reports an un-attributable bounce.

Email parsing Conversion testing

Preview — first 37 lineseml

From: Mail Delivery Subsystem <MAILER-DAEMON@mx1.meridiansupply.example>
To: Maya Chen <maya@brightside.example>
Subject: Delivery Status Notification (failure, headers only) SAMPLE
Date: Mon, 16 Feb 2026 07:48:00 -0800
Message-ID: <p7-dsn-hdrs@mx1.meridiansupply.example>
Auto-Submitted: auto-replied
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status; boundary="=_p7_dsn_p7-dsn-hdrs"

--=_p7_dsn_p7-dsn-hdrs
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

Your message could not be delivered. Only its headers are returned.
--=_p7_dsn_p7-dsn-hdrs
Content-Type: message/delivery-status

Reporting-MTA: dns; mx1.meridiansupply.example
Arrival-Date: Mon, 16 Feb 2026 07:45:12 -0800

Final-Recipient: rfc822; dana@nonexistent.example
Action: failed
Status: 5.1.1
Diagnostic-Code: smtp; 550 5.1.1 SAMPLE - no such user
--=_p7_dsn_p7-dsn-hdrs
Content-Type: text/rfc822-headers

From: Maya Chen <maya@brightside.example>
To: Sam Rivera <sam@meridiansupply.example>
Subject: Standing order for Q1 (SAMPLE)
Date: Mon, 16 Feb 2026 07:45:00 -0800
Message-ID: <p7-dsn-original@brightside.example>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
--=_p7_dsn_p7-dsn-hdrs--

Specifications

Wave: p7
Seed: 20260807
Report Type: delivery-status
Third Part Type: text/rfc822-headers
Returns Body: false
Status: 5.1.1
Line Endings: CRLF (RFC 5322)

Testing contract

Expected to pass

Scenario: Recover the original Message-ID from a DSN whose returned content is text/rfc822-headers rather than message/rfc822.
Expected result: The same Message-ID as the full-message twin is recovered, and the absence of a body is not treated as a parse failure.

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 — DSN Returning Only the Original Headers” 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-dsn-rfc822-headers.eml", "rb"))
print(msg["subject"], msg["from"])