~~Dossier~~ · Open source · mail security

mailxray

Attachment inspection

A service that looks inside untrusted mail attachments without opening them: a Rust workspace of two crates, an analysis library and a daemon with HTTP routes. It reads PDF, Office documents and archives structurally, hunts for active content and macros, and answers with a verdict and a reason code. Archives are unpacked by 7-Zip inside a bubblewrap sandbox, and reports are addressed by the blake3 hash of the content, so one file is inspected once for every recipient.

Domaine

Open source · mail security

Années

2026

État

en cours

Système

Server · Web

ouvrir

github.com/fvaha/mailxray ↗

mailxray — Attachment inspection — **Capture** · No. 18 mailxray — verdict, reason and archive contents, without opening the file.

Ce qu'il fait

01 / 09

Type from magic bytes, never the extension; a mismatch is reported
PDF: actions and JavaScript in nested dictionaries, escaped names, a deep pass over compressed streams
OOXML and OLE: macros, external links and hidden sheets, before the generic ZIP handler
Archives: content tree, compression ratio and protection against bombs
7-Zip inside a bwrap sandbox: no network, no /home, read-only system binds, timeout and output cap
Reports keyed by the blake3 hash of the content, one inspection for every recipient
A clear JSON contract (schema 1) with reason codes and default policy
Never "clean" for a file that was not fully inspected: caps yield partial or suspicious
A reference card in the browser and a demo, with no calls out to the service

Couches

02 / 03

Core — analysis

Rustlopdfzipquick-xml

Type detection and a check that magic matches the name
PDF: recursive walk over action dictionaries, depth capped at eight
OOXML: package, macros and links; OLE: streams and macro payloads
Archives: 7-Zip listing with a tree and compression ratio
The policy layer turns findings into a verdict and reason codes

Daemon

axumbwrap7-Zipblake3

Routes /inspect, /entry, /report and /health, a loopback service with no auth
Sandbox: --unshare-all, read-only binds, one writable work directory
Single-member extraction only for inert types, capped at 8 MB
Reports cached on disk, keyed by the content hash

Contract

JSON schema 1SPEC.md

The spec comes before the code: report fields, reason codes, policy
The webmail never calls the service directly, its backend proxies /inspect and /entry
The milter is not shipped yet: integration means calling /inspect or embedding the crate

Technologies

03 / 03

Langages RustTypeScriptShell 03

Frameworks et outils axumlopdfzip7-Zipbubblewrapblake3 06

Infrastructure Loopback servisbwrap 02

Ce qu'il fait

Couches

Technologies

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