FAQ

How is Koltrix different from Resend / Postmark / Mailgun?

Those are transactional-email-as-a-service products. Koltrix is that plus a full newsletter manager (Listmonk-style) plus a real inbox plus a dashboard your customers can log into. And it's self-hostable from day one.

How is it different from Mailchimp / ConvertKit?

Those are pure marketing tools — no transactional API, no SMTP relay, no inbox, no per-developer infrastructure. Koltrix gives you the foundation under those workflows.

Can I self-host?

Yes. One Docker Compose stack, a single installer script, runs on a 4-vCPU VPS. See Deployment.

What's the data model?

PostgreSQL with schema-per-tenant. Every business table lives in org_<slug>. Cross-tenant data leaks are structurally impossible. See Database.

Do you support multi-organisation users?

Yes. Backed by Clerk organisations. The dashboard ships with an org switcher; switching changes the database schema for every subsequent request.

What about deliverability?

Every new domain runs through an automatic warm-up schedule (50 → 200 → 500 → 2,000 → unlimited daily quota).
Hard bounces auto-suppress recipients.
Rspamd signs every outbound message with DKIM.
Unsubscribe links and List-Unsubscribe headers are added automatically.

Is the API stable?

/api/v2 is the stable surface. /api/v1 is mostly internal (dashboard ↔ API). We'll never break v2 without bumping to v3.

Pricing?

Free for self-hosting. Hosted: Free ($0), Pro ($29/user/month), Business ($79/user/month). Stripe handles checkout.

What's on the roadmap?

Webhook delivery retries with exponential backoff
SDKs for Node, Python, Go (published to npm/PyPI/pkg.go.dev)
Bring-your-own-SMTP for outbound (when you have a vendor you trust)
Per-domain dedicated IPs
Native React / Vue email components