Proof of receipt: fax, registered e-mail or plain e-mail — what is each one worth?

Short answer: the three most common proofs of sending carry very different weight. A fax transmission report proves that a machine answered the number dialled — not that a human read the document, and not that the number was the right one. An e-mail read receipt proves almost nothing: it depends on the recipient's goodwill and can be switched off with a single click. Only the qualified electronic registered letter (ERL), as defined by the European eIDAS Regulation and article L. 100 of the French Postal and Electronic Communications Code, enjoys a legal presumption: it is deemed equivalent to a paper registered letter, with a date of sending and of receipt that can be relied on against the other party. In between sit intermediate solutions — non-qualified electronic registered mail, a bailiff's report, a fax service with qualified time-stamping — which are enough in most situations. The right choice comes down to a single question: what do you stand to lose if the recipient says "I never received anything"?

The real problem isn't sending, it's receipt

Almost everyone aims at the wrong target. People try to prove that they sent something, whereas disputes almost always turn on receipt and above all on the date of that receipt.

Examples abound. Notice to vacate a rented home runs from the moment the landlord receives it. An insurance cancellation must reach its destination before a cut-off date. Disputing an invoice, sending a formal demand, replying to disciplinary proceedings, filing documents ahead of a hearing: in each of these cases, the law or the contract attaches a legal effect to a precise moment. If you cannot establish that moment, your message does not exist in legal terms, even if it physically arrived.

This is where the fax long held its own. A fax gives immediate feedback: the recipient's machine picks up, exchanges a protocol, confirms the number of pages received. The printed report carries the date, the time, the number called, the duration and often a thumbnail of the first page. That is far more than an e-mail sent into the void. But it is still not legal proof in the strict sense — it is an item of evidence that the judge weighs freely.

What a fax transmission report is worth

The transmission report is produced by your own equipment, or by your online sending service. In legal terms it is therefore evidence you create for yourself — something the Civil Code has traditionally viewed with suspicion (no one may create title in their own favour, article 1363, which nonetheless concerns legal acts rather than facts).

In practice, French courts accept the transmission report as prima facie evidence, provided it is corroborated. Commercial case law has long upheld the fax as a valid method of notification between businesses, particularly where the contract expressly provided for it. What the report actually establishes:

Two weaknesses come up again and again. First: the clock. If the time is that of your fax machine, it can be altered, and therefore challenged. An online service that applies a time stamp issued by a qualified trust service provider solves this. Second: the number. Nothing in the report links the number dialled to an identity. Keeping, alongside the report, the source of the number — the "contact" page of an official website printed the same day, the letterhead of a letter received, a company registration extract — changes everything. Many professionals keep a simple transmission register for this purpose, in a notebook with numbered, sewn-in pages, whose chronological order is hard to falsify after the fact.

For sensitive transmissions, archiving the cover page matters as much as the report itself. Scanned on the fly with a document scanner with an automatic feeder and stored as PDF/A, it makes it possible to reconstruct what was transmitted, page by page. We set out this chain in detail in our guide on archiving faxes and evidential value over ten years.

Electronic registered mail: the only one that enjoys a presumption

This is the tier above, and it is the only one grounded in binding European legislation. The eIDAS Regulation (No 910/2014), revised by Regulation 2024/1183 known as "eIDAS 2", defines the qualified electronic registered delivery service. Article 43 sets out the central rule: data sent and received through such a service enjoys a presumption of integrity, of sending by the identified sender, of receipt by the identified recipient, and of accuracy of the date and time.

Under French law, article L. 100 of the Postal and Electronic Communications Code and Decree No 2018-347 of 9 May 2018 organise equivalence with the paper registered letter. In very practical terms, this means a qualified ERL can be used to terminate a lease, give notice or send a formal demand wherever the law requires "a registered letter with acknowledgement of receipt".

Three points to watch, often overlooked:

• Qualified or not? Only providers listed on the French trusted list, published by ANSSI and available on the European Commission's website, deliver a qualified service. A non-qualified "electronic registered" service remains useful evidence, but carries no legal presumption.
• A private-individual recipient must agree. When sending to a consumer, electronic registered mail requires their prior consent. Without that consent, the equivalence falls away. Between businesses, consent is not required in the same way.
• The date of receipt is the date the item is made available, not the date it is opened. A recipient who ignores the notification is deemed to have received it — precisely the opposite of the e-mail read receipt.

The e-mail read receipt: next to nothing

It has to be said plainly: the "request a read receipt" box in an e-mail client has virtually no evidential value. It sends a request that the recipient's software is free to ignore, that the user can decline, and that most corporate mail systems block by default. The absence of a receipt proves nothing, and its presence barely proves more.

More solid technical elements do exist but are rarely used: the message's SMTP headers, which trace the servers it passed through, and the sending server's logs. An administrator can produce a sworn statement. It is cumbersome, expensive, and it still does not establish that the message didn't land in the spam folder.

Plain e-mail is perfectly suited to everyday correspondence. It is not suited to anything where a deadline is at stake. A well-run organisation draws that line in a written internal procedure, and many small businesses formalise this kind of rule in a dedicated lever arch archive file for notifications, maintained by a single person.

Comparison: which proof for which situation

The "health" line deserves a word. Since the general roll-out of MSSanté and the decommissioning of many hospital fax machines, faxing remains tolerated but tightly framed: the CNIL and the Agence du numérique en santé recommend dedicated lines, fax machines placed in restricted-access areas and verification of the number before every transmission. We have developed this framework in our article on medical faxing and health data.

Five habits that strengthen any proof of sending

1. Date the source of the number or address. A time-stamped screenshot of the recipient's official page is worth more than a recollection.
2. Keep the original, not a copy. The transmission report must be archived as it is, in PDF, with its hash, not retyped into a spreadsheet.
3. Use two channels when the stakes are high. Fax on the day, ERL the next: two independent, mutually corroborating proofs cost far less than a case lost on a deadline.
4. Write the clause. Between businesses, a contract can designate the valid notification channel. A clause stating "notifications are validly made by fax to the following number" settles half the disputes in advance.
5. Protect confidentiality upstream. A sensitive document sent to a shared machine ends up sitting in a corridor. A fax machine with PIN-protected secure printing, or failing that a simple opaque document folder for carrying printouts, reduces the risk far more effectively than an internal memo.

How long should these proofs be kept?

The retention period follows that of the obligation they serve to establish. The usual benchmarks, as set out by service-public.fr:

• Commercial contracts and accounting records: 10 years from the end of the financial year (article L. 123-22 of the Commercial Code).
• Civil contracts: 5 years, the ordinary limitation period (article 2224 of the Civil Code).
• Personnel records: 5 years after an employee leaves for payslips on the employer's side, 50 years on the employee's side in practice.
• Residential leases: 3 years after the end of the lease for rent and service charges.

Keeping a transmission report for ten years assumes a medium that lasts ten years. Thermal printouts from older fax machines fade within two to three years: they must be scanned immediately. For paper archives kept nonetheless, an acid-free archival storage box prevents the yellowing and acidification that make a document illegible well before the legal deadline.

Frequently asked questions

Is a transmission report enough to prove a cancellation?

No, unless the contract expressly provides for fax as a valid method of notification. For a consumer contract, the law often requires a registered letter or a qualified electronic equivalent. A fax can support the case, never carry it alone.

Does an electronic registered letter have the same value as a paper one?

Yes, provided it is qualified within the meaning of eIDAS and supplied by a provider appearing on the national trusted list. The equivalence is laid down by article L. 100 of the Postal and Electronic Communications Code. A non-qualified ERL remains a simple item of evidence.

Can a recipient refuse an electronic registered letter?

A private-individual recipient must have consented to receiving ERLs; failing that, the provider must offer them printing and paper delivery. If they have consented and do not check the item, the date of receipt remains the date it was made available — ignorance offers no protection.

What is a screenshot of a transmission worth?

Little on its own: an image can be edited. It gains value when it forms part of a coherent set — the service's sending log, the line's billing records, an automatic confirmation e-mail received in the same second. A judge reasons through a body of consistent evidence.

Do you need a bailiff for an important transmission?

Not as a matter of course. A judicial commissioner's report is justified when the dispute has already arisen, when the opponent is acting in bad faith, or when the stakes far exceed the cost of the report. Beforehand, a qualified ERL covers almost every need.

Do deadlines run from sending or from receipt?

It depends on the applicable text. For residential notice periods, the ALUR Act makes the period run from receipt by the landlord. For other acts, it is the dispatch date that counts, with the postmark as proof. Always check the text before counting the days — this is the most common and most costly mistake.

In summary

• A fax transmission report proves a completed call to a number, not receipt by the right person: it is an item of evidence, not legal proof.
• Only the qualified eIDAS electronic registered letter enjoys a presumption of sending, receipt and date, equivalent to the paper registered letter with acknowledgement of receipt.
• An e-mail read receipt has virtually no evidential value; SMTP headers carry a little more weight, but remain cumbersome to produce.
• Always back up your proof of sending with the source of the number or address, dated the same day.
• Use two channels when the stakes are high: two independent, overlapping proofs are worth more than one hoped-for perfect proof.
• Align retention periods with the applicable limitation period — 5 years under civil law, 10 years in accounting and commercial matters.
• If you are unsure about the countries served or the format of a transmission, see the FAQ and the list of available countries.