FAQ

Real questions from real conversations. We update this when something comes up more than twice.

Can I switch from Mailgun / Postmark / Resend?

Yes, and the migration is usually a one-day job:

Add your sending domain to Koltrix and verify the DNS records. You can keep your current provider live while you do this — DNS coexists fine.
Swap the API call in your code. If you were using Postmark's POST /email, switch to POST /api/v2/emails — the field names are close (to, from, subject, html_body/body_html, text_body/body_text).
Move your suppression list. Export from your current provider, then bulk-add via the dashboard's Suppressions import.
Repoint your webhook URLs. Each provider has its own signing scheme — ours is documented at Webhooks.

For SMTP-based integrations the swap is even smaller: change the host, port, and credentials.

Can I switch from Mailchimp / ConvertKit?

Yes. The newsletter side has feature parity with the obvious things (lists, subscribers, broadcasts, double opt-in, segments, drip sequences) plus things those tools don't ship (transactional API in the same product, a real inbox for replies). Import your subscribers via CSV under Newsletters → list → Import CSV.

The big missing piece compared to Mailchimp is template marketplaces. We ship a few basic templates; for now you bring your own HTML.

How is Koltrix different from Resend / Postmark / Mailgun?

Those are transactional-email-as-a-service products. Koltrix is that plus a full newsletter manager plus a real inbox plus a dashboard your team logs into. Same underlying account means a bounce on a campaign suppresses the address for transactional too — you don't have to wire that yourself.

How is it different from Mailchimp / ConvertKit?

Those are pure marketing tools — no transactional API, no SMTP relay, no team inbox, no per-developer infrastructure. Koltrix gives you the foundation under those workflows. If you're building software and you also send newsletters, doing it in one place beats wiring two products together.

Do you have a free tier?

Yes. The free plan covers up to 3,000 emails/month with one sending domain and one user. Above that, Pro is $29/user/month and Business is $79/user/month with higher limits, more domains, and team features. Stripe handles checkout and the customer portal.

Where does my data live?

Primary region is OVH-Roubaix (France), with off-site backups encrypted at rest. We don't replicate to other regions today — if data residency in a specific country is a hard requirement, please reach out before signing up.

We are not SOC 2 / GDPR / HIPAA certified today.

Can I use my own AI key?

AI features (summarise inbound threads, draft replies, classify messages) run on our infrastructure with a managed model under the hood. There's no customer-supplied API key today. If your account has specific model or data-residency requirements for AI, contact [email protected].

Is the API stable?

/api/v2 is the stable surface — that's the one your code should build against. We commit to never breaking v2 without bumping to v3 and giving you migration runway. /api/v1 exists but is mostly internal (dashboard ↔ API) and may shift; don't depend on it from external code.

Do you support multiple organisations per user?

Yes. The dashboard ships an org switcher in the sidebar; switching changes the active organisation, and any API keys you create are scoped to whichever organisation was active at the time.

What about deliverability?

Every new domain runs through an automatic warmup schedule that ramps the daily quota over several weeks.
Hard bounces (SMTP 5xx) auto-suppress recipients via a global suppression list.
Every outbound message is DKIM-signed and run through an outbound spam check before submission.
Unsubscribe links and List-Unsubscribe headers are added automatically to newsletter sends.
We refuse to send from a domain whose DKIM and SPF aren't both verified.

Deliverability is mostly your DNS hygiene plus your list hygiene. The plumbing is solid; if you're getting spam-binned, run mail-tester.com and follow the fingerprint.

What's on the roadmap?

In rough priority order:

Dedicated IPs per account for established senders
Official SDKs for Node, Python, and Go (published to npm/PyPI/pkg.go.dev)
More sequence triggers beyond subscribe — tag-added, link-clicked, custom event
Native email components (React/Vue) for composing transactional templates as components instead of HTML strings
A/B testing for broadcasts — subject line and content variants with automatic winner picking

These are best-effort, not commitments. If something here is the reason you'd buy, email [email protected] so we can prioritise.

I have a question that isn't here.

Email [email protected]. We respond within one business day and add common questions to this page.