A Factur-X survives email perfectly well: mail systems do not modify attachments. What breaks it is a tool on either end rewriting the PDF: printing to PDF, re-saving from a viewer, compressing, merging, stamping or e-signing after generation. Each of those produces a new file without the embedded XML or without PDF/A-3 conformance, identical on screen and worthless to a machine. The routine that keeps the file intact has three habits: generate last, attach the untouched file, and validate the exact copy you send.
What actually breaks the file
Print to PDF. The classic. Printing a Factur-X into a "new PDF" produces an image of the invoice: attachment gone, metadata gone. Anything with "print" in the workflow is a rewrite.
Re-saving from a viewer. Some PDF readers optimize or linearize on save. Opening to check is fine; saving from the viewer is not. Send the file your generator wrote.
Compressing and merging. PDF shrinkers and merge tools rebuild the document and drop what they do not understand, the declared attachment first. If the customer wants one PDF with annexes, the annexes belong inside the invoice as embedded documents, not merged around it.
Stamping and signing after generation. "Paid", logos, e-signatures applied to the final file frequently break PDF/A conformance or detach the XML. Sign or stamp the source document, then generate.
Body-inlined attachments. Rare, but some mail clients inline a PDF into the message body; forwarded that way, the received "file" is a rendering. Always attach; never paste.
Encryption and password protection are a sixth: PDF/A-3 forbids them, and platforms cannot read a locked file. Transport security is the mail channel's job, not the document's.
The routine that works
- Generate the hybrid file last, after every edit, stamp and signature (the conversion guide covers the build).
- Attach the file as generated, from disk, without opening and re-saving.
- Validate the copy you sent when in doubt: drop the attachment from your own Sent folder into the validator. If that copy passes, what the customer received passes; if they still report a broken file, the rewrite happened on their side, and you can say so precisely.
For recurring disputes, one sentence to the customer's AP team settles most cases: "please process the attached file directly; printing or re-saving it removes the embedded XML."
Frequently asked questions
Can email itself corrupt the XML inside the PDF?
No. Attachments travel byte-for-byte; mail systems do not edit them. Corruption stories always trace back to a tool that rewrote the file before sending or after receiving.
The customer says "there is no XML in your invoice". What do I check?
Validate the copy in your Sent folder. If it passes, their side flattened it, typically by printing to PDF into their archive; if it fails, your last step rewrote the file, and regenerating fixes it.
Can I zip the invoice?
You can, and unzipping returns the identical file. It rarely helps: the file is small, and one more manual step on the receiving side is one more chance someone re-saves it.
How do I add a "paid" stamp or a signature?
On the source document, before generation. If a qualified e-signature on the final file is required, use signing software that explicitly preserves PDF/A-3, and validate afterwards.
Is a password-protected invoice acceptable?
No: PDF/A-3 forbids encryption, and automated systems cannot open it. If confidentiality in transit matters, secure the channel, not the file.
Published 17 September 2026. GetFacturX is not an accredited platform (Plateforme Agréée); transmission over the French network, which foreign suppliers do not need, is operated by an accredited partner platform. This article is not tax or legal advice. Dates, frequencies and amounts are those known at publication and may change; check them before relying on them.