MboxDesk archive guide
How to inspect attachments and damaged MBOX messages
Attachments and malformed MIME are where email archives become difficult. Base64 and quoted-printable encoding can hide the decoded file size, while a single truncated message can cause simplistic importers to stop early.
1. Parse MIME boundaries message by message
Treat each message as its own recovery boundary. Read Content-Type, Content-Disposition, transfer encoding and multipart boundaries without allowing one invalid segment to consume the rest of the archive.
2. Decode before hashing attachments
For base64 or quoted-printable parts, calculate the attachment size and SHA-256 from the decoded bytes. Record filename, media type, disposition and content ID when present.
3. Keep the raw message identity too
Attachment hashes identify decoded files; they do not replace a hash of the raw message. Preserve the raw message SHA-256 together with its source offset and byte length.
4. Report failures precisely
A recoverable failure should identify the source file, offset, segment length, raw hash and parser reason. Continue to the next valid message and include failures in the final archive report.
5. Avoid legal overclaims
Hashes and manifests make an export inspectable, but a desktop utility alone cannot promise chain of custody or legal admissibility. Describe what was recorded without claiming more.