The evolution of the information society towards a fully digital economy has required the creation of legal and technical frameworks to ensure the security of transactions. In today’s environment, trust no longer depends solely on agreements between parties or on an organization’s internal systems.
In Europe, this digital trust is supported by the eIDAS Regulation, which establishes the legal framework for electronic identification and trust services. In this way, eIDAS provides a secure and consistent transaction environment across the European market and has become one of the pillars of digitization in both the public and private sectors.
In this context, Qualified Trust Service Providers (QTSPs) occupy the highest level of assurance. They are not conventional technology providers, but audited and supervised entities that act as trusted third parties to ensure that certain digital evidence (signatures, seals, electronic submissions) retain their legal value over time.
Ensure compliance with European trust standards by analyzing the evidentiary value of your electronic signatures and notifications when comparing a qualified digital service provider with a non-qualified one.
As CustomerComms and MailTeck we are already part of the List of Qualified Trusted Service Providers of the Ministry for Digital Transformation and Civil Service. This recognition qualifies us to offer the qualified service of certified electronic delivery and, as of March 26, we expanded our capabilities with the following services:
- Qualified service in conservation of qualified electronic signatures: Focused on protecting the electronic signatures made, ensuring that the will expressed digitally remains unalterable and valid in the face of technological changes.
- Qualified service in preservation of qualified electronic seals: Important for corporate automation, this service preserves the validity of the seals used by legal entities to authenticate invoices, certificates or massive documents.
Qualified Preservation (QPRES) is the qualified trust service that ensures qualified electronic signatures and seals retain their legal validity over time, even when the original certificates have expired or the cryptographic algorithms have become obsolete. As of March 26, 2026, MailTecK and CustomerComms have been offering this service as Qualified Trust Service Providers (PSCC) recognized on the official list of the Ministry for Digital Transformation and the Civil Service.
What does qualified preservation (QPRES) really mean?
One of the greatest challenges of the digital era is the longevity of electronic evidence. Unlike paper, whose degradation is physical and visible, the “degradation” of an electronic signature is mathematical and technological; its validity is not eternal by default. Signatures depend on certificates that expire and cryptographic algorithms that may become obsolete over time. A document can remain stored for years and still lose its probative value because it is no longer possible to reliably verify the original signature.
The Qualified Preservation Service (QPRES) exists precisely to avoid such a scenario. Its purpose is to preserve the legal validity of qualified electronic signatures and seals over time, even decades after their creation.
At this point it is important to clarify that QPRES is not an electronic archiving or document management service, nor does it guarantee that the document will remain readable in the future. Its function is not to preserve the “archive”, but to protect the cryptographic evidence that proves that a signature or a seal was valid at a specific point in time and that it is still valid from a legal point of view.
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| Dimension | Qualified Preservation (QPRES) | Electronic Records / Records Management |
|---|---|---|
| What it protects | The legal validity of the electronic signature or seal | The document itself (legibility, storage) |
| What does this guarantee? | That the signature was valid and remains legally valid | That the file is available and accessible |
| Applicable Regulations | eIDAS Regulation — Annex III (qualified trust services) | ENS, NIS2, sector-specific data retention regulations |
| Who Can Provide It | Only Qualified Providers (PSCC) supervised by the Ministry | Any technology provider with the appropriate measures in place |
| Validity in the Event of a Challenge | Legal presumption of validity—the burden of proof is reversed | No automatic legal presumption |
| Relevant Time Frames | Decades (mortgage contracts, insurance policies, legal documents) | Varies according to industry regulations |
How does the service work?
The QPRES qualified preservation service operates in three sequential phases: receipt and verification of the signed document, preservation of cryptographic evidence, and periodic resealing before the algorithms lose their robustness.
| Phase | Description | Key Technical Element |
|---|---|---|
| 1. Receipt and Verification | The provider receives the signed/sealed document and verifies that the signature or seal is qualified, was valid, and had not been revoked | Query of European Trusted Lists (TSL) and validation services (OCSP/CRL) |
| 2. Preservation of Evidence | Certificates, revocation lists, and technical metadata are retained. Qualified signatures and qualified time stamps are applied to this set. | Qualified Time Stamp (QTS) in accordance with ETSI EN 319 422 |
| 3. Expiration Management and Re-timestamping | Before the algorithms lose their cryptographic robustness, the system applies new qualified time stamps, thereby maintaining the chain of trust | Periodic re-timestamping in accordance with ETSI EN 319 102-2 (QPRES) |
What does this add from a legal point of view?
When an electronic signature has been preserved using a qualified QPRES service, the eIDAS Regulation establishes a legal presumption of validity: anyone challenging the signature must prove that the service failed or that the evidence was tampered with—not the other way around.
The main value of qualified preservation is not technical, but legal. A document whose signature has been preserved by a qualified QPRES service enjoys enhanced evidentiary force. In practice, this means that the signature or seal is presumed to be valid and authentic. If someone challenges them, it is that person who must prove that the service failed or that the evidence was tampered with, something extremely complex when a qualified audited and supervised provider is involved.
This significantly reduces risks in audits, regulatory inspections and legal proceedings, especially in sectors where documents must retain their value for many years, such as finance, insurance or legal.
Drive the internationalization of your business within the European Union by taking advantage of an interoperable and secure framework of trust that establishes digital identification as a pillar of the European digital single market.
Strategic benefits for critical sectors
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Frequently Asked Questions
What is qualified preservation (QPRES) of electronic signatures?
Qualified Preservation (QPRES) is a qualified trust service regulated by the eIDAS Regulation that ensures that qualified electronic signatures and seals retain their legal validity over time. It is provided exclusively by Qualified Trust Service Providers (QTSPs) supervised by the relevant national authorities, such as the Ministry for Digital Transformation in Spain.
How does QPRES differ from electronic archiving or document management?
QPRES does not store the document itself, but rather the cryptographic evidence proving that an electronic signature or seal was valid at a specific point in time. The electronic archive ensures that the file is stored and accessible; QPRES ensures that the signature on that file remains legally valid even if the original certificate has expired or the algorithm has become obsolete.
What is the legal validity of a document preserved using QPRES?
A document whose signature has been preserved using a qualified QPRES service is presumed to be valid under the eIDAS Regulation. In practice, if someone challenges the signature, it is that party who must prove that the service failed or that the evidence was tampered with—not the document holder. This significantly reduces risk during audits, regulatory inspections, and legal proceedings.
Which sectors need QPRES-certified preservation services?
The sectors with the greatest need are the financial sector (mortgage contracts and loans with statutes of limitations of up to 30 years), the insurance sector (policies and consents whose validity may be challenged decades later), the utilities sector (service contracts), and the public administration sector (administrative decisions and notices). In all of these sectors, the inability to prove the validity of an original signature can have serious legal and financial consequences.
What is the difference between a PSCC and a non-qualified trusted service provider?
A Qualified Trust Service Provider (QTSP) is audited and supervised by the competent national authority (in Spain, the Ministry for Digital Transformation) and is included on the official Trust List. Its services confer automatic legal presumption and are legally recognized throughout the EU. A non-qualified provider may offer technically similar services but without the legal guarantees or the presumption of validity provided by the eIDAS Regulation.
