The Problem: Every Validation Is a Data Transfer
When you use an email validation API — whether ZeroBounce, NeverBounce, Kickbox, or Hunter.io — you’re sending a user’s email address to a server located in the United States.
An email address is personal data under GDPR (Article 4). It allows directly or indirectly identifying a natural person. By transmitting it to an American provider, you’re performing an international transfer of personal data subject to strict rules.
The Legal Framework: What GDPR Says
The General Principle (Article 44)
“Any transfer of personal data to a third country or an international organisation may take place only if the conditions laid down in this Chapter are complied with.”
Authorised Transfer Mechanisms
1. Adequacy decision: the European Commission recognises that the third country offers equivalent protection. For the United States, this is the Data Privacy Framework (DPF), adopted in July 2023.
The problem: the DPF is regularly contested. The Privacy Shield (its predecessor) was invalidated by the CJEU in 2020 (Schrems II ruling). Legal experts consider the DPF faces the same risk.
2. Standard Contractual Clauses (SCC): standardised contracts approved by the European Commission. Most American providers offer them — but they’re insufficient if the company is subject to American surveillance laws (CLOUD Act, FISA section 702).
3. Binding Corporate Rules (BCR): only for multinational groups, a lengthy and costly process.
American Surveillance: The Real Problem
The American CLOUD Act (2018) requires American service providers to communicate stored data upon request from the American government, including data hosted in Europe.
FISA section 702 allows mass surveillance of non-American communications by intelligence agencies (NSA, FBI).
Concretely: even if ZeroBounce or NeverBounce host data in Europe, their American parent company is subject to these laws. An American judge can order them to provide your client data — including the email addresses of your European users.
The CJEU was very clear about this in Schrems II: as long as these laws exist, the guarantees offered are insufficient under GDPR.
Real Fines for European Companies
European data protection authorities have already sanctioned several companies for unlawful transfers to the United States:
- January 2022: a European university sanctioned for using Google Analytics (data transfer to the USA without sufficient guarantees)
- January 2022: same finding for a European e-commerce site
GDPR fines can reach:
- €20 million for the most serious violations
- 4% of annual global turnover of the company
For an SME, even a fine of a few thousand euros (common for procedural violations) is significant.
The Minimisation Argument: “I’m Only Sending an Email Address”
This is the classic argument from American providers. Here’s why it’s insufficient:
1. An email address is already personal data in itself. No additional context needed.
2. Aggregation: large validation providers process billions of addresses. They de facto build a database of your customers’ emails, even without explicitly intending to.
3. Logs and metadata: when you make an API call, you also send your server’s IP address, the time of the call, potentially other headers. This metadata can have value.
4. Consent: have your users consented to their email address being transmitted to an American provider? Probably not explicitly in your privacy policy.
The Solution: A Sovereign API Hosted in Europe
Syvel is entirely hosted in France, on dedicated servers in the EU zone. Data never leaves European territory.
What this means concretely:
- ✅ No transfer to the United States or any other non-adequate third country
- ✅ Processing subject only to European law
- ✅ Not subject to the CLOUD Act or FISA section 702
- ✅ GDPR documentation provided (DPA available, processing register)
Email Validation in Your Processing Register
If you use Syvel, your “Email address validation” processing entry in the GDPR register looks like this:
| Field | Value |
|---|---|
| Purpose | Fraud prevention, data quality |
| Legal basis | Legitimate interest (Art. 6.1.f) |
| Data processed | Email address (pseudonymised on API side) |
| Sub-processor | Syvel SAS, France — DPA available |
| Transfer outside EU | None |
If you use an American API, the “Transfer outside EU” line becomes legally complex to justify.
Checklist: How to Evaluate Your Validation Provider
- Where are the servers hosted? Require a precise answer (data centre, country)
- Is the company subject to the CLOUD Act? Any American company or subsidiary of an American company: yes
- Is a DPA (Data Processing Agreement) available? Mandatory for any GDPR sub-processor
- What is their data retention policy? Are processed emails stored? For how long?
- Are they ISO 27001 or SOC 2 certified? (not sufficient but indicative of security maturity)
Conclusion
Using American competitors is a legal risk for you. This isn’t a commercial argument — it’s a legal reality documented by the CJEU and European data protection authorities.
Every API call to ZeroBounce, NeverBounce, Kickbox, or Hunter.io is a transfer of personal data to the United States. A country subject to the CLOUD Act. A country whose guarantees have been invalidated twice by European courts.
100% Sovereign. Hosted in France, no data transfer outside the European Union. Immune to the CLOUD Act.
Data sovereignty is no longer a marketing argument — it’s a legal obligation. Choosing Syvel means choosing compliance by default. Don’t risk your company’s compliance with extra-European APIs. See also Syvel vs ZeroBounce: an honest comparison to understand what’s at stake.