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Rasket vs Postmark

Both send email over a REST API. Every row below was read from Rasket's own pages and Postmark's own pages on 2026-09-16, and every one of them links to the page it came from.

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Rasket
Rasket is an email API for developers: one REST API, a dashboard and typed SDKs for transactional email and broadcasts, with inbound mail, signed webhooks and an MCP server in the same product and on the same key.
Postmark
Postmark is a transactional email service with six official libraries, an SMTP option and Message Streams, which keep transactional and broadcast mail on separate sending infrastructure.

Key takeaways

  • Extra emails, per 1,000 — Rasket: $0.60. Postmark: $1.80.
  • Entry paid plan — Rasket: $20 a month for 50,000 emails. Postmark: $15 a month for 10,000 emails.
  • Free plan — Rasket: 3,000 emails a month, 100 a day, 3 domains. Postmark: 100 emails a month, and it does not expire.
  • Inbound email — Rasket: Yes. Postmark: On the Pro and Platform plans.
  • Official SDKs — Rasket: Node.js and Python. Postmark: Node.js and TypeScript, Python, Ruby, PHP, Java and .NET.

How they compare

Rasket first, then the same row for the other product. A number beside a cell is the source it was read from; the list at the foot of the page has the link and the date.

Rasket and Postmark compared, row by row
CriterionRasketPostmark
Inbound emailYes Rasket, source 1Receive at your own domain on every plan, delivered as a signed webhook.On the Pro and Platform plans Postmark, source 13The pricing table lists inbound email processing against Pro and Platform.
Transactional and broadcasts on one planYes Rasket, source 2A broadcast travels the same send pipeline as a password reset, on the same plan and the same key.Yes, on a separate Broadcast stream Postmark, source 13Their pricing FAQ says transactional and marketing mail are kept on parallel, separate sending infrastructure.
Signed webhooksYes Rasket, source 3No Postmark, source 14Their webhook guide says Postmark does not sign webhooks with HMAC, and recommends HTTP basic authentication and an IP allowlist instead.
Replay a webhook eventYes Rasket, source 3Send the event again from the dashboard or the API; a replay carries the identical payload under the same event id.Not published Postmark, source 14
Idempotent sendsYes Rasket, source 4An Idempotency-Key is remembered for 24 hours.Not published Postmark, source 15
Versioned templatesYes Rasket, source 5Published versions with typed variables; every send records the version it used.Not published Postmark, source 16Templates are created and edited through the API; the page does not describe versions.
AutomationsYes Rasket, source 6Not published Postmark, source 15
MCP serverYes Rasket, source 7An HTTP MCP server with seven toolsets, plus a setup skill.Not published Postmark, source 15
Markdown docs and llms.txtYes Rasket, source 8Markdown at every docs URL, with llms.txt and llms-full.txt.An llms.txt index Postmark, source 15The index is published; a .md suffix on a documentation URL answered 404 on the day.
Official SDKsNode.js and Python Rasket, source 9Node.js and TypeScript, Python, Ruby, PHP, Java and .NET Postmark, source 17
Free plan3,000 emails a month, 100 a day, 3 domains Rasket, source 10100 emails a month, and it does not expire Postmark, source 13No overage is allowed on it.
Entry paid plan$20 a month for 50,000 emails Rasket, source 10$15 a month for 10,000 emails Postmark, source 13The Basic plan. Fifty thousand emails is $55.
Extra emails, per 1,000$0.60 Rasket, source 10The rate steps down to $0.25 as the Scale ladder climbs.$1.80 Postmark, source 13Basic, between 10,000 and 125,000 emails a month.
Data retention30 days on the self-serve plans Rasket, source 10Custom retention on a Custom plan.45 days, up to 365 with an add-on Postmark, source 13The retention add-on starts at $5 a month and needs a Pro plan.
Dedicated IPAn add-on on Scale Rasket, source 10$50 a month per IP, on Pro and above Postmark, source 13For senders above 300,000 emails a month.
SMTP relayNo Rasket, source 11Sending is the REST API, the SDKs and the MCP server. There is no relay to point a mail client at.Yes Postmark, source 18
DKIM key size2048-bit, one key per domain Rasket, source 12Not published Postmark, source 19
Best forDevelopers who want sending, receiving and broadcasts behind one API keyTeams who want transactional and bulk mail kept on separate streams

Where Postmark wins

Postmark keeps 45 days of history where we keep 30, and sells that up to a year as an add-on, so if you are chasing what happened to a receipt three months ago their default reaches further back than ours. They publish six official libraries to our two, including .NET and Java, and they run SMTP, which we do not. Message Streams are a deliberate design rather than a limitation: keeping bulk mail on separate infrastructure from receipts is a defensible way to protect a transactional reputation, and some teams want exactly that separation.

The verdict

One row here is not a matter of taste. Postmark's own webhook guide says they do not sign webhooks and asks you to use basic authentication and an IP allowlist instead; Rasket signs every event with a timestamp and a secret, and lets you replay one from the dashboard. After that it is price and reach: $15 buys 10,000 emails on Basic and $55 buys 50,000, against $20 for 50,000 on Rasket, with extra mail at $1.80 a thousand against $0.60, and inbound arriving on their Pro tier but on every plan of ours. Postmark is the better fit if you want longer retention by default or a client library in a language we have not shipped.

Frequently asked questions

Is Rasket a good alternative to Postmark?

Yes, and the webhook row is the reason most teams look. Postmark's documentation states that they do not sign webhooks with HMAC; Rasket signs every event and you can replay one from the dashboard. Rasket also includes inbound mail on every plan and charges $0.60 per extra thousand against $1.80. Postmark keeps history longer by default — 45 days against 30 — and has more client languages, so weigh those before moving.

Does Postmark include inbound email?

Postmark: On the Pro and Platform plans. The pricing table lists inbound email processing against Pro and Platform. Rasket receives mail at your own domain on every plan, including the free one, and delivers each message to a signed webhook with its headers, text, HTML and attachments.

Which is cheaper at 50,000 emails a month?

At 50,000 emails a month Postmark's Basic plan is $55 and Rasket's Pro plan is $20. Both figures are read from the two price lists on the same day and both cover the same volume, so this is the comparison's widest price gap; past the quota it stays open, at $1.80 a thousand against $0.60. What the extra buys on Postmark is 45 days of retention rather than 30, and Message Streams keeping bulk mail on separate infrastructure.

Does Rasket have an SMTP relay?

No. Rasket sends over the REST API, the Node and Python SDKs, and the MCP server, and there is no relay to point a mail client or an off-the-shelf application at. If moving means changing an SMTP host rather than changing code, that is a real reason to stay where you are.

Can I migrate from Postmark to Rasket?

Add the domain in Rasket and publish the generated DKIM, SPF and DMARC records; verification runs on its own and you can keep sending through Postmark meanwhile. Then swap the call — POST /emails carries the same fields as their email endpoint, and a template alias becomes a Rasket template published as a version. Point your webhook handler at Rasket's signed events, verify the signature rather than the basic-auth credentials you were checking, and replay a delivery from the dashboard to test it.

Which is better for AI agents?

Rasket, on what each publishes. Postmark serves an llms.txt index of its documentation, which is genuinely useful to an assistant reading up on the API, but on the day we checked there was no MCP server and no Markdown twin at a documentation URL. Rasket publishes an MCP server with seven toolsets, a setup skill, Markdown at every docs URL, llms.txt and llms-full.txt, so an agent can configure a domain and send without a person pasting a key.

Sources

  1. 1. Rasket — http://localhost:3000/features/receiving. Read 2026-09-16.
  2. 2. Rasket — http://localhost:3000/features/broadcasts. Read 2026-09-16.
  3. 3. Rasket — http://localhost:3000/features/webhooks. Read 2026-09-16.
  4. 4. Rasket — http://localhost:3000/docs/idempotency. Read 2026-09-16.
  5. 5. Rasket — http://localhost:3000/features/templates. Read 2026-09-16.
  6. 6. Rasket — http://localhost:3000/features/automations. Read 2026-09-16.
  7. 7. Rasket — http://localhost:3000/features/agents. Read 2026-09-16.
  8. 8. Rasket — http://localhost:3000/llms.txt. Read 2026-09-16.
  9. 9. Rasket — http://localhost:3000/about. Read 2026-09-16.
  10. 10. Rasket — http://localhost:3000/pricing. Read 2026-09-16.
  11. 11. Rasket — http://localhost:3000/features/email-api. Read 2026-09-16.
  12. 12. Rasket — http://localhost:3000/features/domains. Read 2026-09-16.
  13. 13. Postmark — https://postmarkapp.com/pricing. Read 2026-09-16.
  14. 14. Postmark — https://postmarkapp.com/developer/webhooks/webhooks-overview. Read 2026-09-16.
  15. 15. Postmark — https://postmarkapp.com/llms.txt. Read 2026-09-16.
  16. 16. Postmark — https://postmarkapp.com/developer/api/templates-api. Read 2026-09-16.
  17. 17. Postmark — https://postmarkapp.com/developer/integration/official-libraries. Read 2026-09-16.
  18. 18. Postmark — https://postmarkapp.com/developer/user-guide/send-email-with-smtp. Read 2026-09-16.
  19. 19. Postmark — https://postmarkapp.com/developer/api/domains-api. Read 2026-09-16.

Last checked 2026-09-16. Prices and plan contents change. Every figure above was read from the linked page on the date beside it; if one has moved since, the page it came from is the one to trust.

Try it against your own mail

Create a key, verify a domain, and send your first email the same morning. The free plan does not expire.

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