Mailjet (Pathwire/Sinch): EU-first sending from Paris for GDPR setups

What is Mailjet?

Mailjet is a French mail-sending platform, founded in 2010 in Paris, part of the Swedish Sinch group since 2019 (which also owns Mailgun). Mailjet is the EU-first counterpart to Mailgun: same parent group, similar API architecture, but consistent EU data residency with servers in France and Belgium. For Swiss SMEs and fiduciary firms, Mailjet is therefore a direct alternative to Brevo -- both EU-French, both DPA-ready, both GDPR-compliant.

As of May 2026, Mailjet runs primary data centers in Paris (Saint-Denis) and Brussels, both ISO-27001 certified and SOC-2 Type-2 audited. Hosting is explicitly not in the USA -- the Sinch parent has US listing, but the Mailjet service is contractually and technically in the EU. The DPA is automatically available in the dashboard, Swiss standard contract clauses per revFADP can be added on request.

Pricing (May 2026): Free 200 mails/day (~6,000/month), Essential EUR 17/month for 15,000 mails, Premium EUR 27/month for 50,000 mails plus extended marketing features, Custom (enterprise) from 250,000 mails individual. Noteworthy: no hard credit-card verification on the free plan -- account activatable with sender-domain verification.

The API is classical REST with JSON bodies, SDKs in PHP, Python, Node.js, Java, Ruby, Go. Webhooks for event tracking (delivered, bounce, blocked, opened, clicked, unsub, spam) are available on all plans.

Why it matters for Swiss SMEs

Mailjet is the right choice in three specific Swiss SME cases: existing Mailgun experience with EU duty, classical GDPR-compliance need, and sub-50k volume with French-hosting requirement.

Switching from Mailgun experience: Whoever has a team with Mailgun know-how but missed the EU region choice earlier (data in us-east-1) can switch to Mailjet. The APIs are technically different -- not 1:1 compatible -- but the concept is identical: REST endpoint, JSON bodies, webhooks for events, DKIM/SPF setup. The learning curve is small, the compliance win large.

Classical GDPR/revFADP setup: Mailjet has had a mature GDPR compliance path since 2018: DPA in the dashboard, sub-processor list public, EU Standard Contractual Clauses, Swiss standard clauses on request. For a fiduciary firm or law office that needs a revFADP-compliant mail setup without TIA, Mailjet is a direct solution -- equivalent to Brevo, with the difference that Mailjet is somewhat more developer-oriented (classical REST API without marketing-CRM overlay).

Price sweet spot at 15-50k mails: Essential EUR 17 for 15k, Premium EUR 27 for 50k. Mailjet sits in the same price corridor as Brevo Starter (EUR 19 for 20k) but offers slightly more mails per euro in the 15k tier. At very low volume (below 6,000/month) the free plan is fully usable -- 200 mails/day covers a small fiduciary office completely.

The trade-off: Mailjet has 2-3 points weaker inbox rate than Brevo (93 vs 96 percent in 2026 benchmarks). The UI is more pragmatic and less polished than Brevo. Marketing features are solid but less developed than at Brevo. Whoever wants a pure SMTP sending tool: Mailjet. Whoever wants marketing-plus-transactional in a premium UI: Brevo.

How it works

Mailjet exposes SMTP relay, REST API (version 3.1 as standard, v3 legacy) and SDKs.

SMTP relay: Host `in-v3.mailjet.com`, port 587 STARTTLS or 465 SMTPS. User: the API key public component (32-char hex), pass: API key secret. Both generated in the dashboard under "REST API > API Key Management".

REST API v3.1: Endpoint `https://api.mailjet.com/v3.1/send`, HTTP Basic Auth with API-Key-Public:Secret. cURL example:

``` curl -X POST "https://api.mailjet.com/v3.1/send" \ -u "${MJ_APIKEY_PUBLIC}:${MJ_APIKEY_PRIVATE}" \ -H "Content-Type: application/json" \ -d '{ "Messages": [{ "From": { "Email": "invoice@firm-müller.ch", "Name": "Firm Müller" }, "To": [{ "Email": "[email protected]", "Name": "Mrs Berger" }], "Subject": "Dunning No. 2 - Invoice 2026-104", "TextPart": "Dear Mrs Berger, ...", "CustomCampaign": "dunning-stage-2" }] }' ```

The `Messages` array allows up to 50 mails per request -- batched sending without one round-trip per mail.

DNS setup: Mailjet requires two DNS records per sender domain: SPF (`v=spf1 include:spf.mailjet.com ?all`) and DKIM (TXT, selector `mailjet._domainkey.<domain>`, Mailjet-generated). Optional: tracking subdomain (CNAME) for click tracking over own domain. DMARC is the domain owner responsibility. In the dashboard under "Account > Sender Domains" the verification status per domain.

Webhooks (Event API): In the dashboard under "Account > Event API", register endpoint per event type (sent, open, click, bounce, blocked, spam, unsub). HMAC signatures are standard since 2024, header `X-MJ-Signature` -- verification recommended. Retries: 3 attempts over 24h.

Test and monitoring: Mailjet offers a sandbox mode (`SandboxMode=true` in send body), where mail is validated but not delivered. Dashboard yields real-time statistics (sent, opens, clicks, bounces) per day/campaign/sender domain. "Reporting & Analytics" module: CSV export, statistics API for programmatic access.

Mailjet setup in 5 steps

1. 01Create a Mailjet account, verify EU hosting confirmation in settings, add sender domain.
2. 02Generate API key (public/private) in the dashboard, store in .env (MJ_APIKEY_PUBLIC, MJ_APIKEY_PRIVATE).
3. 03Set two DNS records (SPF and DKIM) in Cloudflare as DNS-only, wait 24h for propagation and verification.
4. 04DMARC initially p=none for 14 days, then quarantine. Set up event webhook for bounce/blocked/spam with HMAC verification.
5. 05Sandbox test via `SandboxMode=true` in the API, then production: three test mails to Gmail/Outlook/Bluewin and Mail-Tester.com 10/10.

When Mailjet fits

Mailjet is the right choice when (a) EU-first hosting without TIA is required, (b) volume sits between 5,000 and 50,000 mails per month, and (c) a pragmatic REST API without marketing-CRM overhead is desired.

Concrete cases: A Swiss fiduciary with 80 clients, 1,500 quarterly mails plus dunning waves -- free tier covers it completely. A small SaaS platform for an industry association with 30,000 notification mails/month -- Premium plan EUR 27. A law firm with revFADP duty needing a clear EU-French contract partner -- Mailjet as equivalent alternative to Brevo, somewhat more developer-oriented.

For DACH setups: set SPF and DKIM in Cloudflare as DNS-only, step DMARC cleanly, configure event webhook with HMAC verification. In the dashboard request Swiss standard contract clauses when professional secrecy is involved.

When not to use

Mailjet is the wrong choice when (a) maximum deliverability is needed (Postmark 99 vs Mailjet 93 percent), (b) professional secrecy demands strict Swiss territory -- then Infomaniak or AWS SES eu-central-2, or (c) volume exceeds 100,000 mails per month -- from there SES is more economical.

More pitfalls: setting SPF with `~all` instead of `?all` during rollout -- Mailjet recommends `?all` (neutral) during rollout, then `~all` (softfail), then `-all` (fail). Setting DMARC to `p=reject` immediately without 14 days of observation -- legitimate mails may be blocked. Using v3 legacy API instead of v3.1 -- v3 has a different JSON format that is not portable 1:1; always v3.1 for new setups. Overrunning the free plan in production -- further mails are 429 rejected rather than delayed.

Trade-offs

FAQ

Related topics

Sources

1. Mailjet Pricing 2026 · 2026-05
2. Mailjet API v3.1 Reference · 2026-04
3. Mailjet GDPR and DPA Documentation · 2026-03
4. EmailToolTester -- Best Transactional Email Services Q1 2026 · 2026-04