Is an Online Registered Letter Legally Valid in Portugal?

It is a fair question. If you order the letter online, someone else prints it, puts it in an envelope and hands it over for delivery. Does it carry the same legal weight as a letter you took to a CTT post office counter yourself? (CTT is the Portuguese postal service.) The answer is yes. And it is not a matter of opinion: it comes down to how the process actually works.

In Portugal, a registered letter with AR ("aviso de receção", the signed proof-of-delivery slip) is required or expected in many everyday situations: debt collection, terminating commercial contracts, communications to insurers, formal notices between private parties, employment matters, and communications under Portuguese tenancy law. If you live abroad but own property, run a business or have contracts in Portugal, sooner or later one of these will apply to you. In all of these cases, what gives the letter its evidentiary value is the CTT process, not who stood at the counter.

How the physical process works

When you order a registered letter online, this is what actually happens:

1. The sender prepares the letter content (choosing a template or writing the text) and uploads the PDF to the online service.
2. The letter is printed on physical paper and placed in an envelope.
3. The envelope is lodged with CTT as registered mail and, where applicable, with aviso de receção (AR).
4. The postal worker delivers the letter to the recipient's address, and the recipient signs the AR.
5. The AR, the physical slip with the recipient's signature and the delivery date, is returned to the sender.

The recipient receives a paper letter, in a CTT envelope, delivered by the postal worker. From the recipient's point of view, there is no difference at all compared with a letter posted in person at the counter.

What the law says about the AR as evidence

The aviso de receção is the document Portuguese courts accept as proof that a notice was delivered. The Portuguese Civil Code (Código Civil) establishes that a declaration is deemed received when it reaches the recipient or their representative, or when it was delivered to their letterbox.

In residential tenancies, the law is specific: for communications such as the annual rent update (article 1077.º of the Código Civil) or a formal notice for unpaid rent, the law requires a registered letter with aviso de receção (or hand delivery against signature, under article 9.º of the NRAU, the Portuguese urban lease law). The AR is the evidence a court accepts to confirm the tenant was notified on the correct date. The same logic applies in other contexts, such as debt collection, terminating commercial contracts, or formal communications to insurers and other entities, wherever dated proof of delivery matters.

What the law does not require is that the sender goes to a CTT counter in person. What it requires is that the letter is sent by registered mail with AR through CTT. And that is exactly what an online registered letter service does.

Online registered letter vs certified electronic notification

There is an important distinction here that often causes confusion:

Online registered letter

This is a physical paper letter, sent by CTT with registration and AR. The only difference from the traditional process is that the sender submits the content digitally. The letter that reaches the recipient is physical, the AR is physical, and the CTT registration is real.

Certified electronic notification

This is a 100% digital communication, sent through platforms such as the Portuguese State's electronic notification platform or equivalent services. It has specific legal value in certain contexts, notably court proceedings or notifications from the State, but it is not equivalent to a registered letter with AR for the purposes of the NRAU.

For communications between landlords and tenants in Portugal, such as rent updates, unpaid rent notices or lease termination, the legal requirement is a registered letter with AR sent through CTT. A certified electronic notification does not satisfy this requirement in a private tenancy context.

When to use each one

• Registered letter with AR (posted in person or sent online): rent updates, notices for unpaid rent, terminating a lease, debt collection, terminating commercial contracts, formal communications to insurers, notices between private parties, employment communications. In short, any situation where you need dated proof of delivery.
• Certified electronic notification: communications with State entities, electronic court proceedings, tax notifications, and contexts where the law expressly provides for this channel.

Frequently asked questions