FA-76502 / Email MIME structure / Member archive

Validate Content-Transfer-Encoding across a MIME tree: encoding normalization · case 02

A declared "Base64" or a padded value is reported as an unknown encoding.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Nodes have type, optional cte (default 7bit, case-insensitive, surrounding spaces ignored) and parts or body. Findings [path, reason] use dotted child positions ("" for the root): unknown-encoding (not 7bit/8bit/binary/quoted-printable/base64; the subtree is not inspected), composite-encoding (multipart/* or message/rfc822 using anything but 7bit, 8bit or binary), nested-8bit (an 8bit or binary entity below an ancestor composite that is 7bit), 8bit-in-7bit (a 7bit leaf body containing a character above 127) and long-line (a non-binary leaf with a line over 998 characters).

Why this case matters

Transfer-encoding rules decide whether a message survives relays that only accept 7-bit data.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
padded mixed-case encoding	`[["", "unknown-encoding"]]`	`[]`	Failed

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