Certified email in Spain: what it is and is it legally valid?

A certified email is an email sent through a third party that records when it was sent, when it was delivered and exactly what it contained. In Spain it is valid evidence: a court cannot reject it just because it is electronic (art. 43.1 of the eIDAS Regulation). But only qualified services, listed on the EU trusted lists, carry a legal presumption. Any other service, if challenged, is weighed freely by the judge (art. 326, Civil Procedure Act).

What exactly is a certified email?

"Certified email" (email certificado) is not a legal term. It is the trade name for what the EU eIDAS Regulation (Regulation (EU) 910/2014) calls an electronic registered delivery service. Article 3.36 defines it as a service that transmits data between third parties by electronic means, provides evidence of how the data were handled, "incluida la prueba del envío y la recepción de los datos" (including proof of sending and receipt), and protects them against loss, theft, damage or unauthorised alteration.

In practice, a provider sits in the middle. You send the document through its platform, it delivers it to the recipient and keeps evidence of what happened. At the end you get a certificate or report with that evidence.

The Regulation splits these services into two categories, and almost everything depends on which one yours is:

• Electronic registered delivery service, full stop: any service that fits the definition above.
• Qualified electronic registered delivery service: one that meets the requirements of article 44 (art. 3.37) and appears as such on its country's trusted list.

Is it legally valid in Spain?

Two sets of rules meet here: the eIDAS Regulation, which applies directly, and Spain's Civil Procedure Act (Ley de Enjuiciamiento Civil, LEC). Law 6/2020 on electronic trust services links them in article 3.2: evidence from a non-qualified trust service is governed by article 326.3 LEC, and evidence from a qualified one by article 326.4.

All of them are admissible. Article 43.1 eIDAS says that data sent and received through an electronic registered delivery service "no se les denegarán efectos jurídicos ni admisibilidad como prueba en procedimientos judiciales por el mero hecho de que estén en formato electrónico o no cumplan los requisitos de servicio cualificado" (shall not be denied legal effect or admissibility as evidence in legal proceedings solely because they are electronic or do not meet the requirements of a qualified service).

Only qualified services carry a presumption. Article 43.2 adds that, with a qualified service, the data "disfrutarán de la presunción de la integridad de los datos, el envío de dichos datos por el remitente identificado, la recepción por el destinatario identificado y la exactitud de la fecha y hora de envío y recepción" (enjoy a presumption of integrity, of sending by the identified sender, of receipt by the identified addressee and of the accuracy of the date and time of sending and receipt).

The difference shows when the other side challenges the document:

• Non-qualified service (art. 326.3 LEC). The court follows article 326.2: the party relying on it can ask for an expert comparison or propose "cualquier otro medio de prueba que resulte útil y pertinente" (any other useful and relevant evidence). If authenticity still cannot be established, "el tribunal lo valorará conforme a las reglas de la sana crítica" (the court will assess it according to the rules of sound judgement). In plain terms: proving it is your job.
• Qualified service (art. 326.4 LEC). The document is presumed to have the disputed feature, and the service to have worked properly, if the service "figuraba, en el momento relevante a los efectos de la discrepancia, en la lista de confianza" (was on the trusted list at the time that matters for the dispute). If the other side still challenges it, the checking is at their expense. If the check goes against them, they pay its costs, and if the court finds the challenge reckless it can fine them between €300 and €1,200.

Plain email, certified email and qualified service at a glance

	Plain email	Non-qualified certified email	Qualified service
Admissible as evidence?	Yes, as electronic evidence (art. 299 LEC)	Yes (art. 43.1 eIDAS)	Yes (art. 43.1 eIDAS)
Presumption of sending, receipt, integrity and date?	No	No	Yes (art. 43.2 eIDAS)
If the other side challenges it	You prove it by other means	You prove it: expert evidence or other means (art. 326.2 and 3 LEC)	The challenger has to prove otherwise (art. 326.4 LEC)
Identifies the recipient before delivery?	No	Depends on the service	Mandatory (art. 44.1.c eIDAS)
Where do you check it?	Your mailbox and server	The provider's certificate	The EU trusted lists

What does a certified email prove, and what not?

A good certificate records, for each recipient, when the email was sent, when it was delivered to their mail server and exactly which document went out, with a digital fingerprint (hash) that lets you check later that it has not changed. Some services also record when the message was opened and when the document was downloaded. The open is only an indication; a download from the link sent to that address is the strong evidence that the document reached someone with access to that mailbox.

What a non-qualified service does not guarantee by law is who was sitting at the screen. A qualified one must "garantizar la identificación del destinatario antes de la entrega de los datos" (ensure the recipient is identified before the data are delivered) (art. 44.1.c eIDAS). And no service, qualified or not, makes a wrong address right: whether the address belongs to the recipient is up to you.

A certificate of sending is not a certificate of receipt either. The Barcelona Provincial Court (Audiencia Provincial, the appeal court for each province; Section 13, order 375/2026 of 16 September) upheld the refusal to admit a claim where the creditor produced a certificate that an SMS had been sent to a number nobody had shown belonged to the defendant, plus a courier certificate showing "Estado DESCONOCIDO" (status unknown) and no acknowledgement of receipt. The court's conclusion: delivery had not been proved.

What does a qualified service have to meet?

Article 44.1 eIDAS sets six requirements. The service must:

1. Be provided by one or more qualified trust service providers.
2. Identify the sender "con un alto nivel de fiabilidad" (with a high level of confidence).
3. Identify the recipient before delivery.
4. Protect sending and receipt with an advanced electronic signature or seal of a qualified provider, so the data cannot be changed without it being detected.
5. Clearly tell the sender and the recipient about any change to the data needed for sending or receipt.
6. Show the date and time of sending, receipt and any change with a qualified electronic time stamp.

On top of that, a provider may only start offering a qualified service "una vez que la cualificación haya sido indicada en las listas de confianza" (once the qualified status has been shown on the trusted lists) (art. 21.3). In Spain the list is kept by the Ministry for Digital Transformation and the Civil Service (Ministerio para la Transformación Digital y de la Función Pública), as its own website explains on the basis of article 16.1 of Law 6/2020. That is why the list is the only reliable way to know whether a service is qualified: what the provider's website says is not enough.

How do I check whether a certified email service is qualified?

Here is how:

1. Ask for the exact name of the provider and of the service. Words like "certified", "legally valid" or "fehaciente" (legally conclusive) on a website do not mean qualified.
2. Open the European Commission's trusted list browser and go to the list for the provider's country. Spain's is on eidas.ec.europa.eu.
3. Find the provider. Qualified electronic registered delivery services carry the label QeRDS. When you open one, its type reads "Qualified electronic registered delivery service".
4. Check the status. In the service details, "Current status" must say Granted. "History" shows since when.
5. Match the dates to your sending. Article 326.4 LEC gives the presumption only if the service was on the list at the time relevant to the dispute. If it was qualified after you sent, or lost its status before, it does not cover you.

Two common traps:

• A provider can be qualified for other things (certificates, time stamps) and not for electronic delivery. What has to be on the list is the delivery service.
• A qualified time stamp on the certificate gives a presumption about the date and the integrity of the data it is attached to (art. 41.2 eIDAS), but not about delivery or who received it.

Is a certified email the same as a burofax? Is it "fehaciente"?

No. A burofax is a Correos postal service that, in Correos' own words, "certifica tanto el envío y la entrega como el contenido del documento" (certifies the sending, the delivery and the content of the document) (Correos). A certified email is an electronic service governed by eIDAS. They are different routes with different evidence.

Fehaciente is not an eIDAS category: the word does not appear in article 43. What the law gives is a presumption, and only to qualified services. A non-qualified certified email is valid electronic evidence that the judge weighs with everything else if it is disputed. So it is not accurate to call it fehaciente or to sell it as a substitute for a burofax.

When do you still need a burofax?

Certified email works well when there is a real email channel between the parties. A burofax (or a notary, or a qualified service) is the safer choice in these cases:

1. There is no usual email channel with that person. For the attempt to negotiate that Spain now requires before most civil claims (medio adecuado de solución de controversias, MASC), the law mentions a channel only once, when it deals with limitation periods: "el medio de comunicación electrónico empleado por las partes en sus relaciones previas" (the electronic means the parties used in their previous dealings) (art. 7.1, Organic Law 1/2025). The Alicante courts of first instance accept email if it was agreed as the usual channel or used "de manera reiterada, con un mínimo de tres intercambios en los seis meses anteriores al conflicto" (repeatedly, with at least three exchanges in the six months before the dispute). The Valencia Provincial Court accepts the "e-mail designado en contrato o el que sea habitual en esas relaciones" (email named in the contract or usual in that relationship).
2. The law sets an address. In a community of owners (comunidad de propietarios), each owner gives their "domicilio en España a efectos de citaciones y notificaciones" (address in Spain for notices), and if they do not, their flat counts (art. 9.1.h, Horizontal Property Act). If the owner has not given an email address, email does not replace that notice. We cover it in owners' meeting notices by WhatsApp or email.
3. You expect the other side to contest everything. If you need the burden of proof to sit with whoever challenges, you need the presumption in article 326.4 LEC, and a non-qualified certified email does not give it.
4. You do not have their email, or it bounced. A bounce tells you in time that this route will not work for that person.

If in doubt, use both: certified email plus a burofax to their address. If the burofax comes back undelivered, what happens depends on why: see burofax refused or not collected.

Do the courts accept it?

Where it has been argued most is the MASC, the compulsory attempt to negotiate before suing. The law does not fix a channel: it is enough to have "cualquier documento que pruebe que la otra parte ha recibido la solicitud o invitación para negociar o, en su caso, la propuesta, en qué fecha, y que ha podido acceder a su contenido íntegro" (any document proving that the other party received the request or invitation to negotiate or the proposal, on what date, and that they could access its full content) (art. 10.2, Organic Law 1/2025).

• The Barcelona Provincial Court, at its presiding judges' meeting of 31 October 2025, accepted "correo postal con acuse de recibo, burofax, buro-mail o email, WhatsApp, así como cualesquiera otros medios que permitan dejar constancia del envío y de su recepción" (post with acknowledgement of receipt, burofax, buro-mail or email, WhatsApp and any other means that record sending and receipt), as quoted in order 375/2026 above.
• The Alicante courts presume the requirement is met when there is a documented attempt "mediante medios distintos, como burofax, correo electrónico o SMS, salvo que el requerido demuestre lo contrario con prueba sólida" (through different means such as burofax, email or SMS, unless the other party proves otherwise with solid evidence). They also warn that, if the recipient does not reply, the proof of sending must be backed up with evidence of "la entrega efectiva" (actual delivery).
• The Valencia Provincial Court treats the requirement as met "cuando la comunicación es recibida por su destinatario, aunque no conteste y cuando su actitud pasiva frustra el fin comunicativo" (when the recipient receives the communication, even if they do not reply, and when their passivity defeats its purpose).

The common thread never changes: a real channel, proven delivery and the full content. For the detail on chasing a debt, see MASC by certified email. And once the request has been received, our MASC deadline calculator tells you when the attempt ends without agreement and the last day to file your claim.

What kind of service is ours?

Our certified email service is non-qualified. It sends a document by email to a list from the client's own domain and records, for each recipient, delivery, opening and download with date, time and IP address. Each document carries a SHA-256 fingerprint that can be checked on a public page. The open is only an indication; the download is the strong evidence. It is electronic evidence the judge weighs freely if it is disputed (art. 43.1 eIDAS and art. 326.3 LEC): it is not fehaciente and it does not replace a burofax.

Frequently asked questions

Is a certified email legally valid in Spain?

Yes. No court can reject it just because it is electronic or not qualified (art. 43.1 eIDAS). But only a qualified service carries a legal presumption of integrity, sender, recipient and date; any other is weighed freely if challenged.

Does a certified email replace a burofax?

Not always. It works when there is a usual email channel with the recipient and you can prove delivery. If there is no usual email, if the law sets an address for notices or if you expect a fight over every detail, use a burofax, a notary or a qualified service, or combine channels.

How do I know if a certified email provider is qualified?

Look it up on the European Commission's trusted list browser, in the list for its country. The service must show as QeRDS with the status "Granted". Also check that it had that status on the date you sent.

What if the recipient never opens the certified email?

The certificate still proves sending, delivery to their server and the content. For the MASC, the Valencia Provincial Court treats the requirement as met when the communication is received, even without a reply. Opening is only an indication; downloading the document is what shows access to the content.

What does QeRDS mean?

It stands for qualified electronic registered delivery service. It is the label the EU trusted lists use for these services, the only ones with the presumption in article 43.2 eIDAS.

Sources

• Regulation (EU) 910/2014 (eIDAS), consolidated Spanish text on EUR-Lex, arts. 3, 21, 22, 41, 43 and 44.
• Regulation (EU) 910/2014 (eIDAS), original text as published by the BOE.
• Law 1/2000 on Civil Procedure (Ley de Enjuiciamiento Civil), arts. 299, 326 and 384.
• Law 6/2020 of 11 November on certain aspects of electronic trust services, arts. 3 and 16.
• Organic Law 1/2025 on the efficiency of the Public Justice Service, arts. 7 and 10.
• Law 49/1960 on Horizontal Property (Ley de Propiedad Horizontal), art. 9.1.h.
• Spain's trusted list in the European Commission browser.
• Ministry for Digital Transformation and the Civil Service: electronic trust service providers.
• Correos: registered letter or burofax.
• Barcelona Provincial Court, Section 13, order 375/2026.
• Alicante courts of first instance: criteria on Organic Law 1/2025.
• Valencia Provincial Court: unified civil criteria, 15 June 2026.

This article explains the law and published court criteria as of the update date. It is not a substitute for advice from a lawyer on a specific case.