Mailfence vs Proton Mail

Compare Mailfence and Proton Mail on capabilities, jurisdiction, assurance, and fit for European buyers.

Both listed as alternatives to: Gmail, Microsoft 365, Outlook.com

Mailfence

Belgium· Email Services

Needs review

Shortlist Mailfence when you want Belgian-operated webmail with interoperable OpenPGP, digital signatures, and a light calendar/documents suite—plus optional business private-label or on-prem license. Skip when you need automatic closed E2EE without key management (consider Tuta), a large Swiss privacy ecosystem (Proton Mail), or a minimalist German mailbox (Posteo / mailbox.org).

EU-operated (Belgium)OpenPGP E2EEDigital signaturesMail + calendar + docsCustom domains (paid)B2B DPA available

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Proton Mail

Switzerland· Email Services

Needs review

Shortlist Proton Mail when you want Swiss-jurisdiction, zero-access encrypted email with open-source clients, custom domains, Bridge for desktop mailers, and a public DPA. Skip when you need free-tier IMAP Bridge, fully self-hosted FOSS mail on your own servers, or Workspace-class collaboration depth—consider Tuta, Posteo, or Mailfence among EU peers, or stay on Google/Microsoft if suite lock-in wins.

E2EE + zero-accessSwiss-operatedBridge (IMAP/SMTP)Open-source clientsISO 27001 & SOC 2 (claimed)Public B2B DPA

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Highlighted rows differ between the two products.

Mailfence vs Proton Mail: Snapshot
Feature	Mailfence	Proton Mail
Country of origin	Belgium	Switzerland
Category	Email Services	Email Services
Open source	No	No
Self-hosted	No	No
Headquarters	Belgium	Switzerland
Legal entity	ContactOffice Group sa, Avenue Franklin Roosevelt 47b, B-1050 Brussels (BE 0466.241.584)	Proton AG, Route de la Galaise 32, 1228 Plan-les-Ouates, Geneva, Switzerland (EU representative: Proton Europe sàrl, Luxembourg)
Governing law	Belgian law; Brussels courts (Terms of Use)	Swiss law (Terms; Geneva courts for business/non-US consumer disputes as stated in Terms)
US parent / control	No known US parent	No known US parent
CLOUD Act exposure (indicative)	Low	Medium
Hosting / residency	Primary production servers described as located in Belgium under Mailfence operational control (no intermediary managing servers per security page). No public AWS/GCP/Azure subprocessor list found. Backups stored in locations separate from offices/main DC (providers not named). Payment-card processing path not fully published.	Primary mail storage on Proton-owned servers in Switzerland (vendor security pages). Not marketed as AWS/GCP/Azure inbox hosting. Public privacy policy lists US-group processors for support and payments (Zendesk; Chargebee, Stripe, PayPal) and group support processing in North Macedonia and Taiwan; HubSpot noted for business sales inquiries.
Summary	Belgian secure email suite with browser-side OpenPGP encryption, digital signatures, calendar, documents, and optional custom domains under ContactOffice Group SA.	Swiss end-to-end encrypted email from Proton AG: zero-access inbox storage, open-source clients, custom domains, and Bridge for desktop IMAP clients.
Tags	privacy saas encrypted-email openpgp gdpr productivity belgium	privacy saas encryption e2ee switzerland business free-tier open-source-clients

At a glance: Mailfence vs Proton Mail
At a glance	Mailfence	Proton Mail
HQ / entity	Brussels — ContactOffice Group sa (BE 0466.241.584)	Not listed
Product launch	Mailfence brand ~2013; ContactOffice lineage since 1999	Not listed
Crypto	OpenPGP E2EE + digital signatures; optional password-encrypted messages	Not listed
Hosting	Vendor-operated servers in Belgium (per security page)	Not listed
Open source	No (front-end OSS planned; not current)	Not listed
Self-host	SaaS default; Business license for large on-prem deployments	No (SaaS); clients open source
Commercial model	Free tier + prepaid paid plans; Business packaging (see vendor site)	Freemium + paid consumer and business seats
Independent audit	No public audit PDF found	Not listed
HQ	Not listed	Plan-les-Ouates (Geneva), Switzerland
Legal entity	Not listed	Proton AG (CHE-354.686.492); Proton Foundation supervision
Hosting model	Not listed	Proton-owned hardware in Switzerland (vendor claim)
Bridge	Not listed	Paid plans that include Mail

Key capabilities: Mailfence vs Proton Mail
Key capabilities	Mailfence	Proton Mail
EU-operated (Belgium)	Yes	Not listed
OpenPGP E2EE	Yes	Not listed
Digital signatures	Yes	Not listed
Mail + calendar + docs	Yes	Not listed
Custom domains (paid)	Yes	Not listed
B2B DPA available	Yes	Not listed
E2EE + zero-access	Not listed	Yes
Swiss-operated	Not listed	Yes
Bridge (IMAP/SMTP)	Not listed	Yes
Open-source clients	Not listed	Yes
ISO 27001 & SOC 2 (claimed)	Not listed	Yes
Public B2B DPA	Not listed	Yes

Mailfence

Browser-side OpenPGP end-to-end encryption
Encrypt outbound mail in the browser with the OpenPGP standard so intermediaries—including Mailfence when messages are properly E2EE—cannot read ciphertext. Fully interoperable with other OpenPGP tools (e.g. Thunderbird/GnuPG). Optional password-encrypted messages cover recipients who do not use PGP. Unencrypted mail still sits on servers in the normal webmail model.
Digital signatures and multi-key OpenPGP keystore
Sign messages for authenticity and integrity, and manage keys in-product: generate, import, export, publish, and hold multiple key pairs without browser plug-ins. Default generated keys are 4096-bit per the threat-model page. Passphrase protection of private keys limits crypto operations if only the account password is compromised.
Mail, calendar, documents, and groups in one account
Beyond inbox: shareable calendars, online document storage/editing, and contact groups for collaboration without bolting on a separate US suite. Storage and alias limits scale by plan; free accounts remain suitable only for light personal use.
Custom domains, aliases, and mail protocols on paid tiers
Higher plans add custom domains with SPF/DKIM/DMARC-oriented setup, larger alias counts, and classic client access (POP, IMAP, SMTP) plus ActiveSync where listed. Entry-level free accounts focus on web/PWA/apps rather than full protocol parity—verify the live plan matrix before procurement.
Business admin: API, SSO, private label, optional on-prem license
Mailfence for Business offers control-panel and XML-RPC API user provisioning, SSO and directory hooks (LDAP/AD/CAS), branding, and Belgian cloud hosting with SLA language—or a license to run on customer Linux servers for large deployments. Fit for orgs that need Belgian hosting with admin automation, not a consumer-only mailbox.

Proton Mail

Zero-access inbox encryption by default
Bodies and attachments are encrypted so Proton states it lacks keys to read stored mail. Proton-to-Proton traffic is end-to-end encrypted automatically; external recipients need password-protected messages or PGP/WKD for comparable content protection. Subject lines are not fully E2EE under OpenPGP header rules.
Proton Mail Bridge for desktop IMAP clients
Paid plans that include Mail can run Bridge locally to connect Outlook, Thunderbird, or Apple Mail over IMAP/SMTP while encrypting and decrypting on the device. Free accounts use official web/mobile/desktop apps instead of Bridge.
Custom domains, aliases, and business admin
Paid and business tiers support custom domains, extra addresses, catch-all and groups, hide-my-email aliases, and org admin for seats, storage, and retention policies. Suits teams leaving Google/Microsoft who still need branded addresses.
Open-source clients with published audits
Web, mobile, and desktop clients are published on GitHub with third-party audit reports linked from Proton’s open-source page. The hosted mail backend is not offered as self-hosted FOSS—audit client trust, not full server reproducibility.
Tracker blocking, PhishGuard, and Sentinel
Built-in tracker protection, phishing heuristics, link confirmation, SPF/DKIM/DMARC for custom domains, hardware-key 2FA, and optional Proton Sentinel monitoring for high-risk accounts. Complements encryption with everyday abuse defenses.

Assurance & compliance: Mailfence vs Proton Mail
Assurance & compliance	Mailfence	Proton Mail
Independent security / no-logs audit	Not found No public third-party audit PDF found. Vendor mentions security specialists, bug bounty activity, and inspection openness—not a substitute for a published audit. Privacy policy documents operational metadata collection (not zero-logs).	Vendor claimed Open-source clients with published third-party audit reports (web/desktop links on open-source page). Not a classic VPN no-logs court test; transparency report covers legal orders for accessible account data.
ISO 27001	Not found No Mailfence ISO 27001 certificate claim found on primary security/GDPR/company pages.	Vendor claimed Vendor announces ISO 27001 certification after external audit completed 2 May 2024; Trust Center links a certificate download. Confirm scope and validity at procurement time.
SOC 2 / SOC 3	Not found	Vendor claimed Vendor announces first SOC 2 Type II attestation (July 2025 blog). Report typically under NDA—request from vendor for diligence files.
GDPR / EU data protection	Vendor claimed Belgian controller/processor materials; dedicated GDPR page and technical/organisational measures overview. Confirm roles in your DPA.	Vendor claimed Swiss controller/processor with EU representative; public DPA; GDPR materials for business. Adequacy/transfer mechanisms documented for non-adequate destinations.
US CLOUD Act exposure (indicative)	Partial EU entity (ContactOffice Group sa), no known US parent; servers claimed self-operated in Belgium without named US hyperscaler hosts. No formal public subprocessor inventory; payment processors not named. Assessment residual: partial transparency on data path. Not legal advice.	Partial Swiss entity / no known US parent; inbox content on Proton-owned Swiss hardware with zero-access design. Partial exposure remains via US SaaS subprocessors (Zendesk support; Stripe/Chargebee/PayPal payments) and any account metadata Proton can access under Swiss process. Not legal advice.
Data processing agreement (B2B)	Vendor claimed Downloadable DPA linked from the GDPR page for organisational customers.	Vendor claimed Public DPA at proton.me/legal/dpa forms part of terms when Proton acts as processor; Swiss law, Geneva jurisdiction; general authorization for listed subprocessors.
EU AI Act	Not applicable Email/collaboration suite; not an AI system under typical procurement framing.	Not applicable Core product is encrypted email. Optional Scribe assistant is ancillary; not an AI-centric offering for this catalog entry.

Considerations & known limitations: Mailfence vs Proton Mail
Considerations & known limitations	Mailfence	Proton Mail
No public independent security audit	Medium If vendor risk requires a published audit letter, ISO 27001, or SOC 2, treat Mailfence as incomplete until evidence is obtained offline or under NDA.	Not listed
Closed-source SaaS	Medium Cannot independently review server code or default-self-host like some FOSS mail stacks. Business on-prem license is a commercial path, not community self-host docs.	Not listed
E2EE is opt-in OpenPGP, not automatic	Medium Clear-text messages are operator-readable at rest. Users must encrypt/sign deliberately; training and policy matter for regulated content.	Not listed
Operational metadata retention	Low Privacy policy lists IP, message-IDs, addresses, subjects, and related fields for operations, abuse control, and legal process—not a zero-logs design.	Not listed
Limited public subprocessor inventory	Low Strong first-party claims of internal hosting, but no AWS-style public subprocessor table; confirm payment and support tooling in procurement.	Not listed
US CLOUD Act (indicative)	Low No known US parent; Belgian self-operated hosting narrative. Residual unknown payment/SaaS paths. Not a legal safe harbour guarantee.	Not listed
Weaker defaults outside Proton	Not listed	Medium Mail to Gmail/Outlook/others is not E2EE unless password-protected or PGP/WKD is used. Subject lines are not fully E2EE. Train users or you only protect the Proton-stored copy.
US support and payment processors	Not listed	Medium Zendesk, Chargebee, Stripe, and PayPal appear in the public processor list. They should not see zero-access message bodies, but support content and billing data can touch US-group services—document this in DPIAs.
Bridge requires paid Mail	Not listed	Low Desktop IMAP/SMTP via Bridge is not available on free accounts. Budget seats for users who refuse the official apps.
Hosted service, not self-hosted FOSS mail	Not listed	Medium Open-source clients improve inspectability but you still depend on Proton’s operated backend, uptime, and Swiss legal process. Unsuitable if policy mandates customer-operated mail servers.
Swiss legal orders on accessible data	Not listed	Low Transparency reports show thousands of yearly legal orders for Mail with many complied. Bodies stay encrypted; recovery emails, IPs (when retained for abuse), and similar metadata may still be in scope. Align expectations with counsel.

Fit

Mailfence

Best fit when

You need OpenPGP interoperability and digital signatures from a European webmail, not only proprietary E2EE
Belgian legal entity and self-described self-operated Belgian hosting are procurement requirements
Teams want mail plus calendar/documents/groups without moving to Microsoft 365 or Google Workspace
You need custom domains, aliases, and classic clients (IMAP/POP/ActiveSync) on paid tiers
Business buyers evaluating private-label, API provisioning, SSO/directory integration, or large-scale on-prem license

Poor fit when

Security policy requires a published independent security audit, ISO 27001, or SOC 2 from the email vendor
You want fully open-source server/client stacks you can fork and self-host as default
Every message must be automatically E2EE with no OpenPGP key UX (Tuta-style)
You need Microsoft-class DLP, eDiscovery, compliance archives, and deep SaaS integrations
Zero-logs marketing is a hard requirement (Mailfence documents operational metadata collection)

Consider instead when

When: You want automatic encryption for all messages with minimal key management
Consider: Tuta
Different crypto model; less OpenPGP interop emphasis than Mailfence.
When: You want a larger Swiss privacy suite brand and ecosystem apps
Consider: Proton Mail
Trade Belgian ContactOffice ownership and PGP-centric UX for Proton’s broader product family.
When: You want a lean German ad-free mailbox without suite features
Consider: Posteo or mailbox.org
Simpler mailbox posture; different admin/domain/crypto tradeoffs.
When: You need full Google/Microsoft productivity and compliance tooling
Consider: Microsoft 365 or Google Workspace (accept US-cloud risk) or EU office suites if residency is the driver
Mailfence is not a drop-in M365 replacement.

Proton Mail

Best fit when

Teams that need default end-to-end / zero-access encryption without running their own mail stack
Orgs that want Swiss legal venue and documented resistance to direct foreign data demands
Businesses migrating branded domains off Gmail/Outlook with Easy Switch and Bridge for desktop holdouts
Security-conscious professionals who value open-source clients, published audits, and hardware-key 2FA
Buyers who need a public DPA plus vendor-claimed ISO 27001 / SOC 2 Type II for questionnaires

Poor fit when

Fully self-hosted requirements (Proton Mail is SaaS; clients are open source, not a full on-prem mail server)
Desktop IMAP on free accounts only—Bridge needs a paid plan that includes Mail
Workflows that depend on unencrypted-looking mail to external parties who will not use password links or PGP
Teams that primarily need full Microsoft 365 / Google Workspace collaboration depth rather than encrypted mail first

Consider instead when

When: You want German E2EE email with a different crypto product surface and may not need Proton’s full ecosystem
Consider: Tuta
Compare desktop interoperability and business admin maturity side by side.
When: You want ad-free European mail with strong transport privacy but do not require zero-access E2EE for all stored content
Consider: Posteo
Different threat model: Posteo is privacy-forward without Proton’s zero-access default.
When: You need OpenPGP-centric mail with classic collaboration extras under Belgian operation
Consider: Mailfence
Weigh automatic Proton-to-Proton E2EE UX versus Mailfence’s model.
When: Collaboration suite depth and ecosystem lock-in outweigh encryption defaults
Consider: Google Workspace or Microsoft 365
Accept US-provider jurisdiction and scanning/processing models as tradeoffs.

Open questions for due diligence

Mailfence

Will Mailfence provide a current written subprocessor list (including payment processors and any backup locations) for a company account?
Is any independent security assessment available under NDA for regulated buyers?
For Business on-prem license: exact minimum scale, support model, update cadence, and cryptographic feature parity vs SaaS?
Which plan tiers currently include IMAP/POP/ActiveSync and custom-domain limits for our user count?
How are disaster-recovery backup sites jurisdictions documented in the signed DPA annex?

Proton Mail

What exact data-center sites and any non-Swiss regions apply to your tenant’s mailbox replicas today?
Will Proton provide the full SOC 2 Type II report under NDA and confirm ISO 27001 certificate scope/expiry for your questionnaire?
For business orgs: which users will be private vs non-private, and how will admin recovery work with zero-access constraints?
Which external partners must receive E2EE content, and will they accept password-protected messages or PGP?