Proton Mail vs Runbox

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

Both listed as alternatives to: Gmail, Outlook.com

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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Runbox

Norway· Email Services

Needs review

Shortlist Runbox when you need Norwegian/EEA-hosted IMAP email with custom domains, ad-free subscription economics, and standard clients. Skip when you require default zero-access E2EE—consider Proton Mail or Tuta instead—or when you need a full Microsoft 365-style suite.

Norwegian email hostingIMAP / POP / SMTPCustom domains100% renewable (claimed)Runbox 7 open sourceOptional PGP / S/MIME

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Highlighted rows differ between the two products.

Proton Mail vs Runbox: Snapshot
Feature	Proton Mail	Runbox
Country of origin	Switzerland	Norway
Category	Email Services	Email Services
Open source	No	Yes
Self-hosted	No	No
Headquarters	Switzerland	Norway
Legal entity	Proton AG, Route de la Galaise 32, 1228 Plan-les-Ouates, Geneva, Switzerland (EU representative: Proton Europe sàrl, Luxembourg)	Runbox Solutions AS
Governing law	Swiss law (Terms; Geneva courts for business/non-US consumer disputes as stated in Terms)	Norwegian law; Personal Data Act implementing GDPR (EEA)
US parent / control	No known US parent	No known US parent
CLOUD Act exposure (indicative)	Medium	Medium
Hosting / residency	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.	Core email and account content: servers in Oslo (StackInfra) under Norwegian jurisdiction; systems management Copyleft Solutions AS (Norway). Optional third parties per privacy policy: Stripe, PayPal, Coinbase (US payments); Enom (US domains); Gandi (FR); Domeneshop (NO); JaguarPC (US default web hosting, Norway option); NodePing (US, status page). No known US parent.
Summary	Swiss end-to-end encrypted email from Proton AG: zero-access inbox storage, open-source clients, custom domains, and Bridge for desktop IMAP clients.	Norwegian subscription email hosting from Runbox Solutions AS: Oslo-hosted IMAP mailboxes, custom domains, CalDAV/CardDAV, and optional PGP. Ad-free; not default zero-access.
Tags	privacy encryption e2ee switzerland business free-tier saas open-source-clients	privacy email-hosting gdpr norway renewable-energy open-source-webmail

At a glance: Proton Mail vs Runbox
At a glance	Proton Mail	Runbox
HQ	Plan-les-Ouates (Geneva), Switzerland	Oslo, Norway
Legal entity	Proton AG (CHE-354.686.492); Proton Foundation supervision	Runbox Solutions AS (orgnr 996877027)
Hosting model	Proton-owned hardware in Switzerland (vendor claim)	Not listed
Self-host	No (SaaS); clients open source	Not listed
Commercial model	Freemium + paid consumer and business seats	Paid subscription + trial (no permanent free tier)
Bridge	Paid plans that include Mail	Not listed
Founded	Not listed	Service since 2000; current AS form 2011
Hosting	Not listed	Email: StackInfra Oslo; optional web hosting may default US
Open source	Not listed	Partial (Runbox 7 web app); not self-hosted

Key capabilities: Proton Mail vs Runbox
Key capabilities	Proton Mail	Runbox
E2EE + zero-access	Yes	Not listed
Swiss-operated	Yes	Not listed
Bridge (IMAP/SMTP)	Yes	Not listed
Open-source clients	Yes	Not listed
ISO 27001 & SOC 2 (claimed)	Yes	Not listed
Public B2B DPA	Yes	Not listed
Norwegian email hosting	Not listed	Yes
IMAP / POP / SMTP	Not listed	Yes
Custom domains	Not listed	Yes
100% renewable (claimed)	Not listed	Yes
Runbox 7 open source	Not listed	Yes
Optional PGP / S/MIME	Not listed	Yes

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.

Runbox

Norwegian-hosted IMAP email with full-disk encryption
Mailboxes live on servers Runbox places in a StackInfra facility in Oslo under Norwegian jurisdiction, with full-disk encryption at rest and TLS (including PFS) in transit. Access via IMAP, POP, SMTP, or Runbox 7 webmail suits teams that need standard clients rather than a proprietary-only app.
Custom domains, aliases, and multi-account admin
Host mail on your own domain, manage sub-accounts from a main account, and use many aliases on Runbox domains plus unlimited aliases on customer domains. Plus-addressing and filters help separate identities without running separate mailboxes.
CalDAV/CardDAV plus optional PGP or S/MIME
Integrated calendar and contacts sync over CalDAV and CardDAV with common desktop and mobile apps. End-to-end confidentiality is user-controlled via PGP or S/MIME—not zero-access by default—so operators can still index mail for search and scan for malware.
Ad-free, subscription-funded privacy model
Runbox states it does not show ads, does not use third-party trackers such as Google Analytics, and only scans messages for spam/virus protection—not advertising. Revenue is subscription-based with a public trial period, aligning incentives away from data-mining free mail.
Runbox 7 open-source webmail on hydropowered infra
The Runbox 7 web client is published on GitHub for inspection; the hosted server stack remains largely proprietary. Email infrastructure is advertised as 100% certified renewable electricity in Norway, with additional company offset claims—useful for sustainability procurement checklists.

Assurance & compliance: Proton Mail vs Runbox
Assurance & compliance	Proton Mail	Runbox
Independent security / client audits	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.	Not found Vendor claims minimal logging and short retention windows; no public independent audit report found
ISO 27001	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.	Not found No Runbox ISO 27001 certificate found on primary pages (power supplier ISO 14001 is environmental, not info-sec)
SOC 2 / SOC 3	Vendor claimed Vendor announces first SOC 2 Type II attestation (July 2025 blog). Report typically under NDA—request from vendor for diligence files.	Not found No public SOC 2/3 report located
GDPR / EU data protection	Vendor claimed Swiss controller/processor with EU representative; public DPA; GDPR materials for business. Adequacy/transfer mechanisms documented for non-adequate destinations.	Vendor claimed Norwegian entity; Personal Data Act implements GDPR; appointed DPO; privacy policy documents rights and retention
US CLOUD Act exposure (indicative)	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.	Partial No known US parent; core email in Norway. Medium/partial because privacy policy lists US third parties (Stripe, PayPal, Coinbase, Enom, JaguarPC web hosting default, NodePing). Not legal advice.
Data processing agreement (B2B)	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.	Not found Processor DPA with Copyleft is mentioned; no public customer-facing B2B DPA template found—ask sales/support
EU AI Act	Not applicable Core product is encrypted email. Optional Scribe assistant is ancillary; not an AI-centric offering for this catalog entry.	Not applicable Email hosting product; vendor states no intrusive AI for ad profiling

Considerations & known limitations: Proton Mail vs Runbox
Considerations & known limitations	Proton Mail	Runbox
Weaker defaults outside Proton	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.	Not listed
US support and payment processors	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.	Not listed
Bridge requires paid Mail	Low Desktop IMAP/SMTP via Bridge is not available on free accounts. Budget seats for users who refuse the official apps.	Not listed
Hosted service, not self-hosted FOSS mail	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.	Not listed
Swiss legal orders on accessible data	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.	Not listed
Not default zero-access encryption	Not listed	Medium Unlike Proton/Tuta, Runbox can access stored mail for spam/virus scanning, indexing, and lawful process. Use PGP/S/MIME when E2EE is required.
US vendors on optional product paths	Not listed	Medium Payments (Stripe/PayPal/Coinbase), domain registrar Enom, and default JaguarPC web hosting introduce US processors. Keep web hosting in Norway and minimize US payment data if policy requires.
No public ISO 27001 / SOC 2 / independent audit	Not listed	Medium Assurance relies on vendor policy, Norwegian law, and facility claims. Regulated buyers may need NDA evidence or on-site questionnaire.
Partial open source only	Not listed	Low Runbox 7 webmail is open source; mail backend is proprietary SaaS—no self-host path.
Post-closure and backup retention	Not listed	Low Privacy policy defines multi-month content retention and backup windows after closure (and longer account-info retention for bookkeeping). Request immediate deletion if policy requires faster wipe.

Fit

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.

Runbox

Best fit when

Teams that want Oslo-hosted mailboxes under Runbox Solutions AS and Norwegian law, with full IMAP client freedom
Organizations needing custom domains, multi-account admin, and generous alias patterns without self-hosting an MTA
Buyers who prioritize subscription-funded, ad-free email over free ad-supported Gmail/Outlook tiers
Procurement that values renewable-energy data-center claims and Ethical Consumer Best Buy style ESG signals
Users comfortable managing optional PGP/S/MIME when message-level E2EE is needed for specific threads

Poor fit when

Requirements for default zero-access encryption where the provider cannot read mailbox content (prefer Proton Mail or Tuta)
Need for a fully self-hosted or fully open-source mail server stack
Heavy dependence on Microsoft 365 collaboration (Teams, SharePoint, advanced Exchange) rather than plain email hosting
Mandatory public ISO 27001 or SOC 2 evidence before shortlist—none found on public Runbox pages in this research pass
Optional product paths (default US web hosting via JaguarPC) when a strict no-US-vendor rule covers every SKU

Consider instead when

When: You need default end-to-end / zero-access encryption for all messages
Consider: Proton Mail or Tuta
Runbox uses optional PGP/S/MIME; operator can access stored mail for filtering and lawful process
When: You want a German privacy-oriented host with similar sustainability positioning
Consider: Posteo
Compare jurisdiction (DE vs NO), domain limits, and feature depth
When: You need Belgian email with integrated collaboration extras
Consider: Mailfence
Different encryption defaults and product scope
When: You need global free-tier convenience and suite lock-in
Consider: Gmail or Outlook.com / Microsoft 365
Accept US jurisdiction and ad/suite economics tradeoffs

Open questions for due diligence

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?

Runbox

Will Runbox sign a customer-facing B2B DPA listing all subprocessors for your tenant configuration?
Can optional web hosting and domain registration be restricted to EEA-only providers for your account?
Is any independent penetration test or SOC/ISO report available under NDA?
What is the current employee ownership share and any non-EU shareholding since the 2018 figure on the About page?
Confirm backup geography (privacy policy: secure servers separate from main system—are they also Norway-only?)