Sign a PDF and email it: what holds up and what does not

In the EU, Regulation (EU) No 910/2014 article 25(1) bars denying legal effect or evidentiary admissibility solely because a signature is electronic. In the US, the ESIGN Act (15 U.S.C. §7001(a)) and state UETA law reach the same floor. Neither law names PDF, email, or any particular tool: the act of signing electronically is protected as such.

So the scanned-printed-signed-emailed loop that businesses run daily is not illegal — it is simply evidence-poor.

A PDF that was printed, signed by hand, scanned and emailed carries no binding between the signature and the file's contents: nothing proves which bytes the signer agreed to, nothing proves the file was not edited after signing, and nothing dates the act except mail headers. Identity rests on 'the email came from their address' — an assertion anyone who has seen a spoofed email will discount.

Admissibility is not the standard you should optimise for. The standard is: can you prove it, cheaply, when it is contested?

When the signing happened through a service rather than a scanner, the delivered email can carry a materially different file: a PDF with the signer's PAdES signature over the exact signed bytes, an RFC 3161 trusted timestamp when an authority is configured, the certificate chain, and — at B-LT — the validation data embedded in the file. Plus a verification link whose code is printed in the evidence certificate, so any recipient can check the whole pack without an account.

The email then becomes delivery confirmation rather than the proof itself: the file it carries does its own proving.

Whichever way a signed PDF reaches you, the check is the same and takes minutes: open it in a PAdES-aware validator (Adobe Reader's signature panel, or the EU's open-source DSS validator), see whether the signature covers the whole document, whether the chain validates, and whether the timestamp is present. If a document will matter later, those three facts are worth confirming on receipt — before the dispute, not during it.