Developer docs · InboxRatio Editorial

Postmark email API: SDKs, docs and limits (2026)

Every link below points into Postmark's official developer documentation and was checked on 10 September 2026. We record only what the vendor documents — a field we could not verify at the source is left out, never guessed.

From Postmark's official docs · checked 10 September 2026

Docs, SDKs and limits

Developer docs: postmarkapp.com/developer
API reference: postmarkapp.com/developer/api/overview
SDK languages: .NETJavaNode.jsPHPPythonRubyTypeScriptAs listed in Postmark's official SDK docs
SMTP relay: Yes · SMTP docs
Webhooks: Webhook docs
Pricing page: postmarkapp.com/pricing

From our feature matrix — documented by the vendor

API, SMTP and sending auth

API'Email API' with code examples; API on all tiers
SDKs / client libraries'API libraries for pretty much every programming language' (Node.js, Python, Ruby, PHP, C#)
Public API docsPublic developer documentation
Webhooks'Webhooks' feature (event webhooks on all tiers per comparison table)
SMTP APISMTP service
SMTP relay'SMTP Service'
Transactional emailCore product — 'Transactional Email'
SPF assistance'emails sent through Postmark will always pass SPF by default' (Return-Path includes Postmark IPs/SPF record)
DKIM setupDKIM DNS record generated per sender signature/domain; required for domain verification
DMARC support'full DMARC support with custom Return-Path domains' — custom Return-Path CNAME fixes SPF alignment

Features checked 10 September 2026. ✓ documented · ◐ limited or plan-gated · × documented as absent · — not documented. Documentation is not a measured result — see our methodology.

Pricing snapshot

Paid Postmark plans start at $55/mo (Basic), checked 19 August 2026. Full Postmark pricing by volume

Generated from our datasets — every value verified and dated

Frequently asked questions

Where are the official Postmark API docs?

Postmark's official developer documentation is at https://postmarkapp.com/developer, and the API reference is at https://postmarkapp.com/developer/api/overview. Links checked on 10 September 2026.

Does Postmark have an SDK for Python?

Yes. Python is among the SDK languages listed in Postmark's official docs: .NET, Java, Node.js, PHP, Python, Ruby and TypeScript (checked 10 September 2026).

Does Postmark support SMTP relay?

Yes. Postmark's official docs document SMTP relay sending: https://postmarkapp.com/developer/user-guide/send-email-with-smtp (checked 10 September 2026).

Does Postmark offer webhooks?

Yes. Postmark's official docs cover webhook event notifications: https://postmarkapp.com/developer/webhooks/webhooks-overview (checked 10 September 2026).