Tools / Postmark
About Postmark
Postmark is a transactional email delivery service that sends application email — password resets, receipts, notifications — through a REST API or SMTP. The site says it has been delivering email since 2010 and has sent billions of messages for companies of all sizes. Sending works through an API with official libraries for Node.js, Python, Ruby on Rails, Ruby, PHP, and C#, plus a plain curl example for testing. API requests include a MessageStream field (the sample uses "outbound"), which separates types of outbound email. Developer documentation lives at postmarkapp.com/developer, and you can sign up for a free trial from the homepage. The homepage names IKEA, 1Password, Asana, Webflow, Minecraft, UNICEF, Paddle, Indie Hackers, Litmus, and Moz among its customers. Several customer quotes on the page describe migrating to Postmark from SendGrid or Mailgun, citing deliverability and speed of delivery.
What it does
Postmark handles transactional email: the automated messages your application sends, such as confirmations, receipts, and notifications. You can send via the REST API or SMTP. The homepage positions the product around deliverability — getting email into the inbox rather than spam folders.
How you integrate it
- REST API — the homepage shows a working curl example that posts JSON to
api.postmarkapp.com/emailwith a server token header - Official libraries — Node.js, Python, Ruby on Rails, Ruby, PHP, and C#, with more listed in the developer docs
- SMTP — listed alongside the API in the site's title
- Message streams — API requests carry a
MessageStreamfield (the example usesoutbound)
Customers
Named on the homepage: IKEA, 1Password, Asana, Webflow, Minecraft, UNICEF, Paddle, Indie Hackers, Litmus, Moz, Code Climate, LiveChat, Wistia, Betterment, and InVision.
Pricing
The homepage doesn't show pricing. There is a free trial you can start from the site.
FAQ
What is Postmark? A transactional email delivery service. You send application email through its API or SMTP.
Which languages does Postmark support? Official libraries for Node.js, Python, Ruby on Rails, Ruby, PHP, and C#. The site also shows a raw curl example and links to further integrations in its developer documentation.
Does Postmark support SMTP? Yes. SMTP appears in the site's title alongside the API.
How much does Postmark cost? The homepage doesn't display pricing. It offers a free trial.
Who uses Postmark? The homepage lists IKEA, 1Password, Asana, Webflow, Minecraft, UNICEF, Paddle, Indie Hackers, Litmus, Moz, and others as customers.
How long has Postmark been around? The site says it has been delivering email since 2010.
Alternatives
- SendGrid — transactional and marketing email APIs from Twilio; several Postmark testimonials describe switching away from it
- Mailgun — email APIs for sending, receiving, and parsing; also named in customer quotes as a service people migrated from
- Resend — an email API aimed at developers
- Amazon SES — email sending at scale on AWS infrastructure
Similar to Postmark
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