Tag Archives: DMARC SPF DKIM security

Definition — What is metadata?

The term metadata literally means data about data. It is contextual information that describes, frames, or qualifies a digital asset without being part of it. Metadata is ubiquitous: it accompanies every file, every communication, and every technical record.

• Common examples — A Word document stores the author and last‑modified date. A photo embeds GPS coordinates. An email includes the sender’s IP address and the time sent.
• Primary function — Help sort, search, and manage data across digital systems.
• Side effect — Expose traces exploitable for tracking, surveillance, or correlation, even when content is encrypted.

Which email metadata exist (RFC 5321/5322)?

Email metadata privacy rests on a key protocol distinction. The content of a message (body, attachments) is not the same as its metadata. RFC 5321 (SMTP) and RFC 5322 (header format) codify these details. They define what remains visible and what gets hidden. They include: sender address (From), recipient(s) (To, Cc), subject (Subject), timestamp (Date), unique identifier (Message-ID), and the list of SMTP relays traversed (Received headers).

These data do not disappear when the message is encrypted with PGP or S/MIME. They remain exposed to providers, ISPs, and intermediate operators. In practice, they build a true social and technical map of your exchanges.

For journalists, such traces can reveal supposedly confidential contacts.
For NGOs, they expose partner networks, funders, and local relays.
For businesses, they reveal deal flows, decision rhythms, and working hours. This invisible granularity makes metadata extremely powerful — often more useful for surveillance than the content itself.

What providers can see

Email‑metadata privacy runs into a technical reality. Internet access providers and mail operators have near‑total visibility over headers and flows. At each connection, servers record the sender’s IP address and timestamps. They also log the relays traversed. Even if content is encrypted, this telemetry remains exploitable.

At Google, Gmail infrastructure systematically retains full headers, enabling fine correlation between users and devices.
Microsoft (Outlook/Exchange Online) follows similar policies, integrating these data into anomaly‑detection and compliance systems.
European providers such as Orange or SFR also keep SMTP/IMAP/POP logs, under national and EU retention obligations.

The bare minimum remains visible: the server’s IP address is always exposed. Depending on the client (webmail, mobile app, desktop client), the user’s IP address may also appear in headers. Combined with routing metadata, this exposure is enough to build a technical profile and a **behavioural profile** of correspondents.

Recent events — Why metadata matters in 2025

Late 2025 saw major developments that underscore this column’s relevance. From case law to regulatory sanctions, metadata has become a central issue for sovereignty and digital security.

Updates — Messengers & E2EE

Debates around end‑to‑end encryption and residual metadata are more heated than ever. Highlights from recent months:

• Proton: In June and July 2025, Proton updated its privacy policies. While reaffirming its data‑protection stance, the updates clarified the handling of minimal metadata and system data. This added transparency answers users’ demand for control and validates a sovereign, granular approach. See Proton privacy policies.
• WhatsApp (Meta): The introduction of targeted ads in the “Updates” tab in June 2025 reignited privacy debate. Although private messages remain encrypted, the use of metadata to target ads shows that E2EE does not protect against all forms of data exploitation — a core point of this column. Read more on Meta policy.

Legal & technical events

The email‑metadata issue keeps growing, with concrete developments:

• Case law & employee rights: In June 2025, a landmark ruling by the Cour de cassation reaffirmed that professional emails, including their metadata, are personal data. Employees retain rights of access and rectification, even post‑contract — strengthening the need for sovereign tools to manage/neutralise such data.
• Cybersecurity & emerging threats: A May 2025 report by Barracuda Networks found nearly one in four emails is a threat. “Quishing” (QR‑code phishing) and the use of generative AI to bypass traditional defences are surging. Solutions like DataShielder™ that neutralise content metadata and reinforce authentication (DMARC, MTA‑STS) become critical.
• CNIL sanctions & cyberattacks: Record CNIL fines against Google and Shein in September 2025 for rule‑breaking on trackers confirm a tightening legal regime. In parallel, a massive cyberattack against Google in August 2025 highlighted the fragility of centralised infrastructures and the need for security that does not rely solely on platforms.

Francophone & European statistics on email‑metadata privacy

Email‑metadata privacy is not just theoretical — it’s measurable. Multiple studies across Europe and the Francophone world show the scale of the phenomenon and its impacts on privacy, cybersecurity, and digital sovereignty.

• France — According to the CNIL, over 72% of privacy complaints in 2024 concerned excessive collection of communications data, including email metadata.
• European Union — The EDPB notes that 85% of European providers retain IP addresses and SMTP headers for 6 months to 2 years, despite GDPR minimisation duties.
• Switzerland — OFCOM mandates 6‑month legal retention of messaging metadata, even for secure services.
• Belgium & Luxembourg — Telecom regulators (IBPT and ILR) confirm local providers systematically retain SMTP logs for judicial requests.
• Canada (Québec) — The CRTC and privacy law require proportionate retention. Typical ranges: 6–12 months for SMTP logs.
• Morocco — The ANRT obliges operators to retain email and connection metadata for at least 12 months for judicial purposes.
• Senegal — The CDP confirms providers must store mail logs for a minimum of one year, under data‑protection law.
• Monaco — The CCIN applies a regime close to the French CNIL, with regulated retention of metadata.

These figures show that even in European and Francophone democracies, email‑metadata retention is standard practice, often in tension with GDPR’s minimisation principle.

Exploitation risks — profiling & surveillance via metadata

Email metadata is a formidable analysis tool. By aggregating IP addresses, SMTP headers, and timestamps, one can reconstruct a social graph: who exchanges with whom, how often, and in what context. This alone can map entire communities — journalists, NGOs, or companies.

In business, the same data feeds ad‑profiling or industrial espionage. Large platforms can correlate technical addresses with purchase behaviour, link them to geolocation by IP, or to sensitive production cycles.

Public authorities also leverage metadata for lawful surveillance and national security. The boundary between legitimate use and abuse is thin — especially with tracking pixels embedded in marketing emails. The EDPB and CNIL recently reiterated that such trackers require explicit consent.

Combining these vectors — advertising, espionage, state surveillance — metadata becomes a central lever to anticipate behaviours, select targets, and steer decisions. Abusive exploitation undermines privacy and opens the door to systemic drift.

EU legal framework — GDPR, ePrivacy & email privacy

Email‑metadata privacy is governed by a complex European legal arsenal. The GDPR requires actors to limit collection to what is strictly necessary — yet communications metadata is often kept well beyond the minimisation principle.

The ePrivacy framework, via Article 5(3), strengthens prior‑consent requirements for tracking devices, including invisible pixels inserted into marketing emails. In 2025, the CNIL reiterated that these electronic trackers constitute personal data and require explicit user choice.

Meanwhile, some national authorities, like Italy’s Garante, set precise limits — e.g., retention of employees’ emails should not exceed a few days, unless a specific legal obligation applies. These doctrines illustrate the fragile balance between operational need and privacy.

At EU level, the debate persists: should massive metadata retention be allowed for cybersecurity and justice, or should proportionality prevail to avoid generalized surveillance?

Classic defences — mail protocols & their limits

To mitigate email‑metadata privacy risks, several mechanisms are widely deployed. SPF, DKIM, and DMARC strengthen sender authentication and reduce spoofing. MTA‑STS and TLS‑RPT aim to enforce secure delivery by mandating TLS between mail servers.

These improve flow integrity and authenticity, but leave transport headers and IP addresses intact. In short, they don’t protect metadata itself.

Content encryption solutions like PGP or S/MIME add an important confidentiality layer for message bodies. However, they only hide the body and attachments. Sensitive fields like Subject, To, From, and Received headers remain visible to providers or SMTP relays.

Some users turn to VPN or Tor. These can anonymise the client‑side IP, yet do not stop servers from retaining headers. Defence remains partial.

Sovereign countermeasures — DataShielder™

Conventional tools partially protect email‑metadata privacy. To go beyond, Freemindtronic deploys sovereign countermeasures with DataShielder™: a hardware‑anchored architecture that compartmentalises usage and reduces exposure.

DataShielder HSM NFC stores keys and digital identities offline. Physical isolation prevents leakage to cloud or disk, ensuring local, segmented control.

DataShielder HSM PGP desktop introduces encapsulation: before sending, the message is encrypted offline with AES‑256 CBC PGP using segmented keys. This first sovereign lock makes content opaque before it ever reaches the mail system.

Your mail system (PGP, S/MIME, or E2EE service) can then apply its own encryption. The result is double encryption that neutralises content metadata such as Subject, attachments, or MIME structure.

Only transport metadata (IP addresses, traversed servers, timestamps) remains visible, as required by SMTP routing.

✪ Diagram — Double encryption combines offline encapsulation (DataShielder) with the messenger’s E2EE for maximum resilience.

Sovereign flow — offline encapsulation & double encryption

The sovereign flow implemented by DataShielder™ follows a precise chain designed to neutralise content metadata and compartmentalise usage, reducing what third parties can exploit to the bare minimum.

1. Offline encapsulation — The message and its attachments are first encrypted offline with AES‑256 CBC PGP using segmented keys stored in DataShielder HSM NFC or DataShielder HSM PGP desktop. Content (text, attachments, MIME structure) becomes fully opaque.
2. Double encryption — Once encapsulated, the message is handed to the mail system, which applies its own encryption (PGP, S/MIME, or E2EE, depending on the service). Outcome: two locks.
3. Neutralisation of content metadata — Subject, attachments, and MIME structure are contained within the encrypted payload, preventing provider‑side analysis.
4. Persistence of transport metadata — Only IP addresses, relays, and timestamps remain visible, as they are indispensable to SMTP routing.

This architecture introduces analytical friction that exceeds typical automated correlation capabilities, creating cryptographic noise that makes profiling or interception costlier and less certain.

End‑to‑end encrypted messengers (E2EE) & residual metadata

Services like ProtonMail, Tutanota, Signal, Matrix, or WhatsApp ensure that only sender and recipient can read messages. No third party can decrypt the content.

However, even with E2EE, some information remains visible. Transport metadata (origin IP, SMTP relays, timestamps) cannot be hidden. Some content metadata like Subject, size, or attachment type (MIME) may also be accessible to providers.

This is why the DataShielder™ sovereign approach complements such services. By encapsulating message and files in AES‑256 CBC PGP offline via segmented keys before sending, the content becomes opaque to servers. The E2EE service then applies its own encryption, yielding double encryption: offline sovereign + native E2EE.

Beyond email — metadata in all communications

The metadata‑privacy problem extends beyond email. Every digital service produces traces, often invisible to users yet highly exploitable by providers, platforms, and authorities.

• Instant messaging — Slack, Teams, Messenger, Telegram log connection times, groups joined, and associated IPs.
• VoIP & video — Zoom, Skype, Jitsi expose call duration, participants, and relays.
• Mobile telephony & SMS — Operators retain call metadata (calling/called numbers, cell‑ID, duration, rough location).
• Web browsing — Even with HTTPS, IP address, DNS resolutions, and TLS SNI reveal destinations.
• Social networks & cloud — Platforms like Facebook, Google Drive, Dropbox exploit access logs, devices used, and file‑sharing histories.
• VPN & Tor — These mask origin IP but don’t erase logs retained by certain nodes or operators.

Alone, these bits seem trivial. Aggregated, they form a behavioural profile capable of revealing work habits, social ties, even political or union leanings.

Other infrastructures — IoT, cloud, blockchain & technical traces

Metadata privacy also covers digital and industrial infrastructure. Each technical interaction leaves an exploitable trace, often more persistent than human communications.

• Connected objects (IoT) — Voice assistants, medical wearables, or home sensors continuously emit activity logs, including usage times and unique identifiers.
• Cloud storage & collaboration — Services like Google Drive, OneDrive, Dropbox keep access timestamps, devices used, and sharing histories, even if files are encrypted.
• DNS & network metadata — Every DNS lookup, every TLS SNI, every firewall log exposes destinations and frequency, independent of content.
• Blockchain & crypto — Transactions are immutable and public; addresses form permanent metadata, traceable at scale via graph analysis.

These stacks show metadata has become a structural invariant of the digital realm. It cannot be removed, but must be neutralised or compartmentalised to limit abusive exploitation.

Cybersecurity & espionage — legitimate vs abusive uses

Metadata has ambivalent value. On one hand it is essential to cybersecurity and justice: connection logs, IPs, and timestamps let SOC teams and investigators detect anomalies, identify attacks, and build evidence.

On the other hand, the same data becomes an espionage instrument when exploited outside legal bounds: state or industrial actors can map relationships, anticipate strategic decisions, or track sensitive organisations in real time. Intrusive ad campaigns also rely on covert correlation mechanisms.

DataShielder™ addresses abusive uses: offline encapsulation, double encryption, and identity segmentation reduce local traces and complicate correlation. Legitimate uses (security, judicial investigations) remain possible via transport metadata, while content metadata gets neutralised.

Real‑world use cases — NGOs, journalists, SMEs

The metadata issue is not theoretical — it translates into concrete risks. Three scenarios where DataShielder™ changes the game:

Journalists — Metadata can reveal a newsroom’s confidential contacts. With DataShielder HSM PGP, messages and attachments are encapsulated offline, then re‑encrypted by an E2EE service (ProtonMail, Signal). Sources gain protection against abusive correlations.

NGOs — Partner networks, funders, and local relays leak through timestamps and IPs. Combining DataShielder HSM NFC for identity segmentation with encrypted mail helps compartmentalise exchanges and limit espionage or intrusive surveillance.

SMEs — Decision cycles, deal flows, and working hours can be inferred from SMTP headers alone. Deploying DMARC + MTA‑STS plus DataShielder HSM reduces spoofing attacks and strengthens confidentiality of internal communications.

Practical guide — reduce email‑metadata exposure

Protecting email‑metadata privacy blends standards with sovereign measures. A practical checklist for companies, NGOs, and public bodies:

• Domain authentication — Enable SPF, DKIM, and DMARC (reject) to curb spoofing and reinforce trust.
• Secure transport — Deploy MTA‑STS and TLS‑RPT to enforce TLS between mail servers.
• Tracker neutralisation — Block automatic loading of remote images and use anti‑pixel filters to prevent clandestine collection.
• Retention minimisation — Limit mail‑log retention. Italy, for instance, caps employees’ email retention to a few days.
• Sovereign encapsulation — Use DataShielder HSM NFC or HSM PGP desktop to encrypt offline messages and attachments with AES‑256 CBC PGP and segmented keys before sending.

Together, this combination reduces exposure, strengthens digital sovereignty, and makes abusive metadata exploitation harder.

Weak signals 2025→2027 — emerging trends

Expect intensifying debate around email‑metadata privacy and digital communications. Several weak signals already point to structural shifts:

• Tighter tracker controls — New European guidance will likely restrict invisible pixels and other trackers, with stiffer penalties.
• DMARC & MTA‑STS by default — Adoption could become quasi‑mandatory, enforced by major operators and national regulators.
• Targeted & proportionate retention — Authorities are considering stricter limits on metadata retention to avoid massive, permanent surveillance.
• Mass‑correlation AI — Rising AI tools will cross‑reference logs, DNS, IPs, and public data, accelerating intrusive correlation.
• Sovereign + cloud hybrid — A mixed model combining offline encapsulation (DataShielder) with cloud E2EE may become the standard for sensitive organisations.

Bottom line: mastering metadata will be a strategic priority between 2025 and 2027 for EU sovereignty and cybersecurity.